OK, this is absolutely not spam in any way, shape or form, this just me providing SoCal mountain bikers with a link that is absolutely incredible.
About two months ago I was riding and just happened to start up a conversation with a guy as we were both finishing our rides. After talking for about 30 minutes he told me about a site called www.geoladders.com
where you can check out new routes, post your ride results (time, distance, HR, calories, etc) for those routes, organize rides with other riders in your area and get some very accurate updates on current trail conditions for each of the routes.
In addition to this, every time you post your results you receive points (points are based upon the difficulty of a given ride as well as a couple of other factors you can read about on the site) and these points allow you to "climb the ladder" of other riders in your area. As you climb the ladder you get ranked (I'm currently #17) and, if you should chose to do so, you can redeem your points for no strings attached prizes (gloves, computers, gel packs, etc.).
The other cool thing about the ladder and posting your results is the fact that you can really see how your ride times compare to those of other riders who are doing the same routes and trails that you've ridden.
The best part about the whole site, IMHO, is the fact that you can learn about new trails, get route directions & descriptions, see topo and other maps and ask riders who've recently been on those trails what to expect.
At the moment, the largest number of routes are in the Orange County area but they seem to add a couple of new routes each week and there are several routes in the Pasadena, Riverside and San Bernardino areas as well.
I honestly think this may be the best moutain biking site I've ever heard of. Check it out even if you don't live in SoCal but, if you do, you REALLY need to take a look.