If you're looking for killmail dumps, this is to the place to go! API (History)

Individual killmails can be fetched here: API (Killmails)

Looking for an API to post killmails to zKillboard? API (Posting Killmails)

Want to know the prices that zKill uses to value killmails? API (Prices)

Documentation on R2Z2 can be found here: API (R2Z2)

An API for pulling entity statistics: API (Statistics)