Thanks for the detailed suggestions, those are all good points. An api-type feature, like you are suggesting, is on the way, and the other suggestions are now on the list.
Happiness all the way!
Just posted an update to the site. The API is now available (via http://hapylink.com/hapify.php?link=) and links are also shorter now.
You could do with a bookmarklet to make generating links easier.
Perhaps you could add a feature to allow URLs to be prefixed by http://hapylink.com/ to then change them into the final link. For example: http://hapylink.com/http://www.foxnews.com/ would return a page with the resulting Hapylink. Diggbar does it like this and makes it so easy to use.
Could you make the resulting links /slightly/ shorter (optionally, perhaps)? I'd like to use this on Twitter but Twitter would shorten (or at least truncate) these URLs again as they're a bit long, I think.
A logo would be cool.