Normally I don't go for the geeky "look what I can do" iPod hacks such as using it to run Linux. However, here's one that might actually be useful and worth the time of setting up.

Using sound files which mimic the sounds of a touch-tone telephone, your can dial a telephone just by selecting a file (or playlist) on your iPod.

For instructions which make it simple enough to be useful, see the MacMerc.com.

Note that the instructions say that external iPod speakers are necessary, but I was able to do it fine with just my normal headphones. (I haven't tried it with earbuds.)