I don't really any design at the moment... :S
warning, following is personal opinion by a non-expert
Why would people want to use your service ?
Get a smaller url.
Who'll use it ?
Mostly Rick Rollers and Twitter folks.
-> So having engine.puffinhost.com is still kind of long. It also doesn't clearly identify that you'll be linked to another site and won't actually be going to engine.puffinhost.com. Having something that speaks for itself would probably make it much more effective.
Biggest competitor
TinyURL.com
They're website is seriously ugly and clutterish for such a simple tool.
I'd try to keep the main page as empty and clear as possible. Many people aren't computer literate and probably don't grasp the idea at first. So try to keep the main page a clean and simple as possible. IE put fairly big links at the bottom of the page to the other stuff the site might contain instead of a sidebar or including them in text.
edit, shrink.com seams available.
