I've been using TinyURL for awhile, and it's a good companion to SLURL, since Second Life URLs can get so very loooong. I tend to run my SLURLs through a Firefox toolbar tool so the newly-tiny URLs can be copied-and-pasted for brevity — this is especially important for emails, where line breaks mangle lengthy addresses.

Recently, I found out about Snipr (also known through several other names like the slightly longer "Snipurl"), and appreciate that I can create a custom, memorable nickname instead of relying on a cryptic jumble of letters & numbers, no matter how short. (Looks like they've been around since 2000, so I'm surprised I didn't hear of them earlier.)