Maybe it's a programmer thing (although that wouldn't explain why this is from BoingBoing, right?), but this is (probably embarassingly) my kind of puzzle:
- Involves applying a relatively simple algorithm
- Benefits from some external memory but not a comprehensive storage solution
- Doesn't require a lot of unverifiable intuitive leaps
- Can be brute-forced near the end
- Solvable over lunch
And just so you know I'm wonderful, a solution is: dadbeddedabadbadbabe.