External Mods to locate specific blocks? [closed]

I'm looking for clay blocks, and they are quite hard to find. I know that I could simply edit my inventory and add more clay blocks, but that doesn't quite have the same "fun" factor as setting out in a boat and fighting tooth and nail to wrest every last clay block from the hands of those filthy creepers.

Are there any external utilities that will at least point me towards the nearest patch of clay? I saw this image in the minecraft chat that looks like it could be what I want, but I don't know how that screenshot was taken (or how to use it).

Edit: Thanks to the mod, I discovered a cache of 88 clay blocks not 20 units from my spawn!

Solution 1:

Minecraft X-Ray Maintenance Branch was one of the map viewers on the Programs and Editors page of the Wiki. I haven't personally used it, but the wiki says it supports Windows, Mac, and Linux. The program allows you to view your map and make certain blocks glow (ex. clay, diamond).

Edit:

Since the program mentioned above seems to not have an .EXE download available, I found another program named MineViewer. It allows for real-time layer slicing.

This would take a little bit of time, but to find clay, I suppose you could set the colour of all blocks other than clay to white or gray (you can make your own colour schemes!), and slice down to sea level (so the rest of the terrain doesn't get in your way).

Solution 2:

For the sake of completeness, if you happen to be on a Mac, there's the very excellent MCMap Live, which has a built-in block finder:

Here, it's highlighting clay blocks.