I think Les' journal idea is a great one. I usually have a camera with me and do the same, keeping a file of "current" negs and contacts (these seem to go back about 2 years at any given time), that I might print and revisit until I feel I can file them away for a while, and even then I might take out some that have been filed for a while.
I shoot a variety of subjects. I favor certain things like architecturals, portraits, and landscapes. I used to do a fair amount of street photography, but that's just not what I'm thinking about lately. I started photographing birds a few years ago as a way to learn about birds, because New York is an interesting region for birding. Bird photography accounts for 90% of what I shoot in color or 35mm these days.
When I feel I need to do something different I'll do pinhole for a while or 35mm B&W or try some unusual film like XX cine stock or Fomapan T200 or I'll use a lens that I've neglected for some time.
On the other hand, I can see a danger in becoming too eclectic and losing focus, so I don't feel inclined to abandon the subjects that I'm most familiar with.