Not sure - but I read around where some members use them - they place bids for you - some external program you download from the internet?

I figure you tell them how much you want to bid and what you want to bid on etc and then they submit the bid on your behalf.

I just googled "snipe tool" just then and got a heap of hits for free downloads that claim to be ebay specific

Not game to post links incase that's advertising and the Mods zap me, so maybe just have a google?

I like sniping manually, so never bothered to investigate before