[iamthad]

If you consider yourself a "good hacker", then "anything [you] might find interesting" is exactly what the guidelines say is on-topic:

On-Topic: Anything that good hackers would find interesting. That includes more than hacking and startups. If you had to reduce it to a sentence, the answer might be: anything that gratifies one's intellectual curiosity.

http://ycombinator.com/newsguidelines.html