I'm kind of happy my game isn't popular enough to have been pirated yet.
Wait... 
I'm working on my own commercial release, which would've been finished months ago if I wasn't so lazy, and I when I got to the point that I started thinking about copy protection I thought back to crypto class and started coming up with some really elaborate stuff. Then I decided, so what if people steal it? As someone mentioned, people that pirate games aren't generally those who would've bought the game anyway (and I'm convinced a great many
can't, keep in mind the world is a lot bigger than the US and there are a lot of people on the wrong side of an unfavourable exchange rate). The counter-argument is that some of those people would've bought the game if they couldn't steal it, but I don't think that's really true with the independent software market. It usually takes a modicum of internet savvy to pirate just as it takes a degree of internet exposure to even know that independent games exist, which I think separates people that have a way of doing things when it comes to aquiring software from those who know it's out there and just want it. (Also, These are often people who are aware that demos aren't necessarily truely indicative of the value of a game.)
So in that sense it can't really hurt all that much. After all it's been a part of the broader industry since the first games on magnetic media. Maybe my opinion is skewed by developing freeware, but it may even help. It's exposure, after all. If a hundred people pirate a game and one of them buys it, that's one sale rather than one hundred non-sales. If half of those pirates are impressed by a title and recommend it to a friend or two, that's potentially a great number of sales rather than one hundred non-sales. All of those people, pirates or not, might pay a little more attention to your future releases. Again, that's just a difference with independent games thanks to the relatively low market penetration. If you steal a Halo or Mario game, there's no positive effect for the developers since there's nobody you could possibly tell who doesn't know about the title and who gives a fraction of a shit.
I can only speak for myself of course, but I'd much rather every non-buyer pirate my games rather than simply not play at all.
(today i got lost on the way to tigsource)