Which obviously isn't to say I don't believe in luck, per se; just that if I work hard, I'll have better luck in life; and similarly, if I'm generally a good person and behave well at work and in personal life, good karma will probably generally follow me as well, in some aspects of life.
I'm talking about online karma, too. Earlier this year, an employee was fired from The Warehouse for abusing the management on Bebo; last week, some poor schmuck was refused sick leave because his boss saw that he'd posted, "Still trashed — sickie WOOHOO!" on Facebook. Employers are googling potential employees, and checking out Facebook and Bebo, and for a lot of people that's not a good thing. It does, however, prove that Facebook and Bebo's potential for evil is limitless.
I used to put a lot of crap on my diaryland blog; whining about exes, work, and friends. I also hurt people's feelings, and some people found my blog who weren't meant to find it, and it almost ruined one friendship. These days I try to keep my blog content so that anyone can read it — friends, family, boss, co-workers, editor, ex-boyfriends... I don't want to offend anyone, and if someone stumbles onto my blog for any reason, it's good to have a clear conscience and know there's nothing on there they can't read.
The internet's a public forum, and I think it's just good common sense to keep issues with other people private. Bitch about it to your friends or your partner privately; there's no call to take it public. And, if I don't get any good karma out of it, at least I'm stopping the bad karma.