I hate it when I see people use the wrong "lose" - and it's an incredibly common thing. Other efforts include too instead of to, no instead of know and infer instead of imply. I'm not saying I'm Mr. Right when it comes to grammar (in fact, I've learnt (or learned?) a fair bit from Paul at work on this one), but I think that's usually the exception to the rule. The basics, as I've listed out here, should be a bit of a no-brainer. Then again, some people would place a lot more value on other things rather than just being able to spell ... and they'd probably be right :)