Last session was 4 players + DM (me) but it varies a lot, between 2-5 players is normal. Currently I have 2 core players, 1 semi-core, and frequently have a drop-in player as well. I find that 2-3 players is ideal for minimum GM stress, but 4-6 PCs is ideal for party survivability in 3e, so there's a slight problem there.