For the past 5 days I have been riding at McAllister Park during my lunch breaks. In 30-40 minutes I can get in a 3-5 mile ride on nice single track and double track dirt trails. The trails offer some moderate climbs and descents and lots of winding narrow paths through Live Oak forests.
Today I found a program for my HTC Mogul Windows Mobile phone, GPS Cycle Computer, which uses the phone internal GPS to track my position, speed, elevation, and ride time. This picture is from Google Earth with the KML file of todays ride; 4.13 miles in 35 minutes.

You can see this on an interactive map by clicking this link to Google Maps.
Over the past week I have ridden about 37 miles in the park. My favorite trail is the “Red” trail with all the unmarked trails that branch off it. Most are through the shade of the Oak Trees, and there is a large ravine with some short but steep descents. This is a good area to help me regain my old technical riding skills without the danger of tumbling down 400 feet of mountain if I crash.