Sword Fern
The Sword Fern is a hardy fern that does well in San Diego. Sword Ferns prefer shaded to part shade environments, but can tolerate full sun as well. They require a moderate amount of water.
Sword Ferns spread quickly and can create a sort of low lying hedge that can be pruned back and shaped fairly easily when grown along a concrete walkway or along low lying concrete curbs or walls.
For more info on sword ferns, check out these sites:
http://bss.sfsu.edu/holzman/courses/fall00projects/swordfern.html
http://en.wikipedia.org/wiki/Polystichum_munitum
Right now, I've got sword ferns in 1gal containers for a mere three bucks each!