It's bad enough that you used http://www.tinyurl.com 's idea, but you also pretty much copied the short url example (mapquest link) and the "uses of it". So my question to you now is, why compete with tiny url? TinyURL may not have come up with the idea originally, but their name is certainly more catchier than shortu. Oh and BTW, that google ad. is very annoying stuck there in the middle of the page.
Apart from the afformentioned, you've done a good job.