The Sierra Club's home page – find out what's going on at the macro level.
The Angeles Chapter site – for a more local focus.
Many of us like what the Hundred Peaks section offers, which tend to be big, multi-peak day hikes.
The Wilderness Travel Course offers a great opportunity to learn the do's and don'ts of travelling in the back country.
The Orange County Sierra Singles section offers great social events and trips to Mammoth and elsewhere.
We're trying to get more involved with the 20's and 30's section. This section offers many different types of outings.
The ICO section does good work with youngsters in both LA County and Orange County.
On a related note, the Easy Hikers Committee offers hikes that are in-line with the committee's title.
The Little Hiker's Committee is becoming active again, which will focus on hiking opportunities for children. I'll update this site with a link to their site in the future.
Let's start with the National Forest Service site, then consider more specific locations such as the Angeles National Forest, San Bernardino National Forest, and Sierra National Forest. For the rest, you're on your own.
Now let's consider California State Parks, such as San Jacinto, or Crystal Cove, or even Malibu Creek.
The Irvine Ranch Land Reserve offers some very interesting hiking opportunities in areas typically not open to the public. These outings are lead by a docent who has been trained in the local flora and fauna. These outings are typically moderate paced, and sometimes theme based such as learning about animal tracking or the wild flowers in the area. These are usually free. Check out the offerings on their web site, under the “Let's Go Outside” heading.
The Palos Verdes Peninsula Land Conservancy is similar to the above, but focused on PV. They have limited hiking offerings, but lots of other stuff going on. Check out their happenings in the pull down menu under Activities, then select the Calendar option.
Ever check out the site for Adventure Hikes in the San Gabriels? Some very interesting stuff in here. Much of it requires ropes and/or netting. Yikes!
This site has some nice information on hikes in the San Gabriels.
This is a really good site for looking up local hiking, particularly if you are traveling someplace to which you've never been. Pick the state, city, and see what's in the area.