Mobitopia 2.0 (mobitopia.com) is to the mobile web what del.icio.us is the the PC web, a place to store and share links to interesting sites. If you aren't familiar with the huge Web 2.0 success that is del.icio.us, this Wikipedia article will get you up to speed.
Mobitopia's motto is "Mobile Links That Don't Suck (TM)". Seeing as anyone can register and post public links to the site there's also the admonishment, "Please don't add mobile links just to add them, there are too many mobile directories out there filled with crud." It seems to be working as the crud level at Mobitopia is pretty low.
You don't need to register to use Mobitopia as a portal. Search is by tag or title and you can browse by date, title or, my favorite, random. There are over 500 links on Mobotopia - not bad for a site launched just last August. For registered users Mobitopia also has some of the usual trappings of a mobile social site like profiles and friends although there is no messaging.
There's also a Mobitopia/Twitter mashup that you can set up to have an SMS containing the "Mobile Link of the Day" sent to your phone.
Mobitopia is Russell Beattie's site. Russ used to write the best blog on mobile topics. It was reading Russ' blog that got me started thinking and eventually writing about mobile stuff. The blog is still online although it's no longer updated. If you haven't seen it you should definitely take a look. Russ had some great things to say and did so with great style.
I've added Mobitopia to Yeswap.com in the Portals/WAP section.