I've used esnipe but now I've moved to phantombidder.com
It charges a set fee per successful bid instead of a value based fee used by esnipe. You can also sign up for unlimited bids.
Another good thing is that you can set up bidding groups. If you win one item in the group, the remaining bids are canceled so you don't risk winning multiple items if you're away and can't cancel sniping bids manually.