Keeping track of multiple bases in Minecraft

In Minecraft, I often lose track of some of the chests that I've created, as well the bases that I've made, so I keep losing some of the items that I've collected. Is there any efficient way to keep track of multiple bases in Minecraft, besides writing down the coordinates of each base and using the F3 key to travel to each one?

One easy and organizable way would be to use Rei's minimap mod. It is a really nice mod where you can create waypoints that can be seen on the mini map and in the game. Most servers allow it, but double check if you're not sure.

Another simpler way would be to make pillars out of bright, noticable materials (birch wood, snow, etc.) and putting glowstone/torches at the top so they can be seen easily from a distance. If your bases are far away from each other, you could try making smaller waypoints along the way, to stay on track.

Note that some servers will ban or kick players who make large, 1x1 towers (thank you SevenSidedDie), so be careful. If you really had the time you could make a fancy 3x3 or 4x4 tower, or you could just make 3-5 high tall pillars, here and there, denoting a path.

Or you could make a trail of some sort on the ground (gravel is nice). The problem with this one is that it would require a good bit of time for something you will use minimally.

Make copies of your map and put one in an item frame in each base. When you walk nearby it will show up on your map if you are carrying one with you. It's a bit glitchy but it works pretty well if you don't want to install a mod just for this. Another easy way is to craft a journal and write the coordinates in it for each of your bases, then toss it in an ender chest so you can grab it from anywhere.

If you're going to use a mod, you may as well use mystcraft or dimensional doors to warp directly between bases and cut the map part out altogether.

If you're playing in single player and willing to "cheat" you might want to use teleporters. Easy to make, fast travel, and safe. This video explains how to make them using command blocks.