I have been searching and bookmarking hiking and mountainbiking sites for a while now but I just found this one which is well above average:
localhikes.com
Like on most hiking sites, you can find descriptions, lengths, hike times, driving directions and maps of the area for numerous trails... However, this one is the only free site I have seen so far that also shows the hike route on a topographic map, the elevation change chart, and even a few pictures of every trail. I which they had a little more hikes though.