I used to send friends 'useless links of the day'. Sometimes amusing, sometimes not. Usually either interesting, useless, or some combination. Occasionally useful ones crept through. These would be disseminated via ICQ or Jabber.
I found I was getting quite a few though, so started a page on my web page. Then I could have an archive, and organise them to some degree.
Not a blog in the sense of journalling, just links. What I can now do, is have a button in Galeon (or whatever browser I'm using on the day), be looking at a page, and click on the button. The button brings up a page that lets me attach a comment or two, a title, and then it can email the link away.
The page in question is a Mason component. Happily uses Cache::FileCache to store the URLs, both in their original form and in Shorl keyword and password form. The Shorl part keeps URLs short in emails, and Shorl also logs hits. (That said, I used to have the web page of links go through a modified merlyn script (from WebTechniques) and thus had statistics that way.)
Future expansion (assuming I get around to it) will see things like sending a weekly digest, sending via Jabber/IRC. And stuff. Naturally, this is all done for my own edification and enlightenment rather than any practical purpose.
So, from little concepts, fun things grow.
But, yes, it does look very easy to create such a URL shortening service. (Just think, purl or scribot could have their own; if they haven't already.) It is, after all, just a mapping of URLs to keys and back again.
Arbitrary semi-historical note: MASL was first, iirc. Then TinyURL which has/had shorter links (not just from the domain name. Then Shorl which allows you to see how many times a given URL was accessed, and uses more memorable keys.
(Iain/Koschei/Spoon/ict/something different every day)