I'm a big bit.ly fan and recently I registered a shorter URL to use for short links - and I went for lrnja.net. I sat down to configure my new domain with bit.ly, and it was very straightforward (I'd almost say "designer-proof"! /me ducks).
- First: register your domain
- Log in to your registrar's control panel and add an A record*
- That's it! In about 24 hours, you'll be able to shorten with your domain
* or a CNAME if you want to use a subdomain of an existing domain.
Bit.ly has excellent instructions here: lrnja.net/bitlydomain