Over the past four years I pretty much developed my own methods of sniping at the last second to get items that I really want. It's a gigantic pain, there's no doubt, and it depends greatly upon whether or not my connection is up to snuff, but I think I've only lost two out of fifty or sixty auctions I've sniped.
It also helps that my last second bids are usually far more than most other people looking at the item are willing to spend. I think that alone makes a world of difference. Most people who were also sniping the same item I was pretty much entered minimum bids at the last second, maybe at most half a buck or a dollar. Problem is that I usually toss in what I'm willing to go up to, plus an extra amount depending upon whether the shipping is reasonable, if it's really rare, stuff like that. So when someone else is sniping for two quarters and I'm sniping for an additional $20 or so...
After early experiments with eBay I learned that I shouldn't bid until at least the last few hours if I can't be near a computer and, if I do, there are a few subtle tactics you can use to keep off most generic snipers out there. For example, if you want to do well try picking a really strange dollar amount as a maximum bid above what you're willing to spend. I find most snipers like nice, round numbers but if you go a bit above that...
For example...
Willing to spend: $25
What I bid: $26.63
It's just a tad bit of extra security. For most of the items I buy people will see my bid (well, not really, since at that point it isn't anywhere near $25) and when people start nickel and diming it in the last three minutes...well, it almost never reaches the price that I bid.
To be fair, I tend to bid on anime DVDs, games, wallscrolls, posters, and other similar items that tend to get a moderate amount of traffic but nothing staggering. If this was meant for an item that everyone wants (ie: a PSP)...well, that would involve a whole other kettle of fish that I haven't touched in a long time.