The Fistful of Bitcoins paper by Meiklejohn et al has some nice heuristics. i.e.

HEURISTIC 1. If two (or more) addresses are inputs to the same transaction, they are controlled by the same user; i.e., for any transaction t, all pk ∈ inputs(t) are controlled by the same user.

HEURISTIC 2. The one-time change address is controlled by the same user as the input addresses; i.e., for any transaction t, the controller of inputs(t) also controls the one-time change address pk ∈ outputs(t) (if such an address exists).

Are there any others that are particularly effective?

Is it possible to bootstrap my clustering, for instance, maybe if some people have already associated a certain cluster with Kraken or Satoshi Dice, is this information available?