map my run is pretty good. Gives you a graph with altitude and stuff. You can also search for runs in your area that other people have uploaded. I've only managed to get it to follow roads though, so I don't think its useful for canals, parks etc. You can turn on the satellite view, like in Google Earth, etc.
Cheers, but will it work on my ipod touch 1st gen?
I don't think they do applications for ipods. What I do is just time myself and map the run on the comp before hand. From that you can work out your average speed over the whole run. On from that I suppose you could do time splits every mile or so by knowing where the mile marks are and just pressing a button on your watch as you go through.