Samantha - I'm using Runmeter for the iPhone, and cannot recommend it highly enough. It has heaps of extra stuff that I don't blog here, like graphs, maps, full history, vocalised announcements, infinitely-variable activities, intervals and so-on.
It's a cracking piece of kit, but only available on iPhone, it seems. No other phone OS is supported, and the iPod can't use it as it needs the GPS and data capabilities.