My gf has a set of cards, each containing a map of an area of San Francisco and suggesting a route for an interesting walkabout in said area (I found them on Amazon here). One of these 'city walks' was to Bernal Heights, which is an interesting little community nestled atop a rather steep and elevated hill:
The main street running through Bernal Heights, Cortland Ave, is quaint and has a number of nice coffee shops and restaurants - it makes for a great leisurely if somewhat uphill stroll.
The elevation of the heights is such that they offer some of the best views of the city. (It's debatable whether it's better to walk up to Bernal or Twin Peaks - the latter allows you to see both the Pacific and Bay sides of the city, but Bernal Heights offers some better views of the city's southern districts, like SoMa, the Mission, and Potrero Hill).
Here's a panorama that I took of the view looking North-West to South from the Bernal Heights Hill. The hill on the far left is Twin Peaks, while in the center we're looking straight down through the Mission District to downtown. The hill just to the right of the center is the Potrero Hill neighborhood.
The last image I'll post here is a shot that I took looking North-East toward San Francisco's less famous but actually more impressive Bay Bridge (linking SF to Oakland). Looking at these photos, one can begin to understand why SF has such a reputation for being a hilly city. Those buildings down there are within easy walking distance, and yet the difference in elevation is rather startling.
As usual, I've made a Picasa Web Album with many of the other photos I took while on the walk. Given their close proximity to the BART subway system (Glen Park Station is just next to Bernal Heights) and the great views, I'd reccomend a walk through the area to anyone visiting the city.