Here are some ideas for some Elevators.
 What is an elevator?
An elevator is a type of vertical transport system that carries people and goods to certain floors in a structure. They are sometimes known as lifts. In Minecraft these can be used to transport players in a adventure map, be used on server clouds, and a WHOLE lot more! Plus These can be of much use on servers that have a spawn for their players so they can get to multiple floors (like on a cloud server) to access another portal.
 Water elevators
The following elevators require water to transport players up and down.
 Tube design
Note: Do NOT attempt to ride this in Survival Mode because the player will take fatal damage (unless made with one block wide with the water and the player stays "outside" near the edge).
- Build a base 4 blocks wide and 6 blocks tall.
- Start to build up to your 2nd Floor.
- If you haven' t done so, build 3 blocks up from the 2nd Floor. Then seal the top up.
- Smash out a hole on the 1st Floor 3 blocks high and 2 blocks wide. Do the same on the 2nd Floor
- Smash out the ceiling and put water in all the corners.
- OPTIONAL - mining out blocks from one side of the elevator and replacing them with glass panes or fences allows a player to ride "half-in, half-out" of the water shaft, and allows a player in Survival to breathe.
 Breathable water elevator
A way to make a water elevator that is adequate to use in survival mode.
- Any Block
- Infinite water source
The only restraint for this elevator is that the size has to be at the very least 2 blocks in length on at least one side. It can be however large on the other dimensions. When one is finished with the shaft they need to fill it. Place the water source so that it is not flowing then place the signs right above the water then water above the signs and repeat until it is to the size that you want. This kind of elevator is also faster than the regular version of a water elevator.
 Floating water elevator
If you want to make it be just floating water with no shaft, you can use ice.
- Any Block (sand or gravel works well)
Create a pillar of sand or gravel and on the side of every other block, place ice. Then, break the pillar and create a new one with a gap of one block between the new pillar and the ice. On the new pillar, place torches on the side of every other block, making sure none of them are next to ice. When the ice has all melted, destroy the sand/gravel pillar. You should be left with a pillar of floating water that you can swim up.
 Boat Elevators
Elevators to move boats can be built using signs. The basic design is shown in the image below. The left elevator has dirt walls, the right one has glass plane walls, making this design close to transparent. This design also works after Minecraft 1.5 and can be used as a lock in a canal. The video below shows such an elevaton in action.
 Boat design
|YouTube Video (view on YouTube)|
 Simple minecart elevator
Note: This elevator only works going up.
To create the elevator, all you need is a 1x1 shaft, down (or up) to the place where you want to go. Once the shaft is finished, you will need to divide the number of blocks by either four if you are in Single Player, or five if you are in Multiplayer. This is to figure out how many Minecarts and Ladders you will need.
After you have all the needed blocks, continue onto the next set of instructions.
- Fill up the shaft all the way to the top by Towering. Make sure that there is room for you to get out of the elevator after the ride is over!
- Slowly go down, placing ladders on the wall, and placing Minecarts on top of those. IMPORTANT! Make sure the Minecarts are close enough so you can transfer to the one above you without moving!
- When you reach the bottom of your shaft, you're done!
- OPTIONAL: Create another shaft next to your elevator with Water at the bottom, so you can jump right in.
To operate, just stand underneath the first Minecart and hold the Right Mouse Button. If you did it right, you should go straight up to the top.
For other purposes, pigs with saddles also work as an elevator.
 Piston Elevator
There are many different wiring designs for piston elevators. The principle of them is that you get pushed up into the air using pistons. They can be extremely fast, and you can both ascend and descend with some designs. There are two popular kinds of piston elevators: block and zipper. The block kind has pistons that push pistons out to push you up. The zipper kind has stairs that push you up in a zipper fashion.
 Up & Down
The up and down elevator has a maximum height of 12 units due to the limited amount of blocks a piston can move. This design is also relatively slow, but thanks to its small form factor and simple redstone circuits this can be suited for buildings.(no longer works in alpha)
|Up and Down Video (view on YouTube)|
Fast piston elevators are quicker than more traditional ways of gaining height, like ladders and powered minecarts. They are designed to be practical.
Zipper elevators feature pairs of pistons stacked vertically. The stair version can be open on two opposite sides, and is useful for giving views above ground. The no-stair version can only be open on one side. They have one major drawback, as SMP can cause a malfunction in the timing and cause the elevator to cease function. Also, adding a 1x2 piston on the top to push you onto a platform once you have reached the top to prevent the player from falling back down can be beneficial.
|Zipper Elevator Video (view on YouTube)|
Spiral elevators feature a vertically stacked spiral of pistons. Because the pistons and wiring surround the player while they ascend, this type is no good for giving a clear view. They are however, more suitable for SMP as they do not transport the player as quickly and so are less likely to trap the player due to lag.
|Spiral Elevator Video (view on YouTube)|
These piston elevators are slower than more traditional ways of gaining height, like ladders and powered minecarts. While not practical, they are designed with style in mind.
 Single column elevator
Single column elevators made to reach the top quicker are usually short due to their need for complex redstone wiring methods. It can be simplified by using sand or gravel as a floor and pistons to push sand. However, this elevator is much slower.
|Single column elevator Video (view on YouTube)|
|Another single column elevator Video (view on YouTube)|
Secret Entrances and false dead ends trick players who are unaware of a potentially expansive area. The trick in disguising these is to find a place where the switch is either hidden or thought to do something else.
 Two Way (Paternoster elevator)
An elevator that can go two ways but requires a lot of redstone work and lots of space, the video on how to do this is here 
NOTE: This video is outdated and no longer works.
 Command Block Elevators
Beside from the minecart elevator, command block elevators can be made with some special effects, and are the quickest of all the elevators. The principle is that you can hit a button wired up to a command block with the /tp @p x y z command. (Alternatively, you can replace @p with your name, creating a player-specific elevator.) The most basic design is to have the command block behind the button. To get a little more complex, you will need a bit more room, or use repeaters. The basic objective is to have a command block with the /tell @p Going to [floor name] command, then a few moments later, having a command block with the previously mentioned /tp command to do the main part of going to a floor. Note that if you are using this with a high-rise building, you may need to create more than one elevator cab for serving more than a few floors, since this type of elevator may get a little big trying to serve 35 floors in one cab.
Another technique is to have two command blocks per floor, one sending the user one floor up, the other sending them one floor down. Align all the x and z coordinates, so that the player stays on one spot relative to the two columns, and can simply click repeatedly to ascend or descend multiple floors.