My only gaming regrets come from WoW. No, I don't mean investing time in it, but quite the opposite. I played from just before Ahn'Qiraj (so the end of 2005) to the end of 2007; almost 2 years exact. I was a bit of a newb starting out, as we all were, and was pretty useless with keeping my money.
I distinctly remember a level 60 Gnome Warrior, on Jubei'thos, offering to sell a 'blue' weapon around my level, which was mid to high 20s, I think. I asked him how much he wanted, and he said "20g". Crap, I only had like... 80 silver. That's .8g, for those who don't play WoW. I explained that I couldn't buy the weapon, and apologised for wasting his time.
"Screw it" he said, "I'll give it to you anyway. I only picked it up when running a guildy through an instance, it's no big deal."
And he gave it to me. Being a massive newb (I was only 13 when I started, so yeah), I only really got exasperation and impatience from people, and for someone to just be nice was unheard of. Then later on, when I got to level 40, he helped me pay for my mount. He was a friendly guy to me, and from what I got was that he was older, probably around 20s or something. Typical WoW player. The patience he showed to a young lad of 13/14 was remarkable.
Anyway, I took a brief hiatus a bit later from that point, and when I came back, he was gone. Character deleted. Bummer.
Anyway, after I quit in '07, I eventually came back, about 3 months ago (about). I already had 2 level capped characters in BC, so I knew the mechanics of the game, and I picked up the rest very easily. Being so 'leet', I tended to be impatient and even a bit rude with newbies, because, hey, I didn't want to waste my time with em, despite starting on a new server. Well one day, recently I was being a bit of a douche to a person who took a sarcastic remark as a serious one, and thought I needed their help. I remembered this guy from 3-4 years prior, and I simply felt ashamed for my actions. This guy, my in-game role model, was kind enough to randomly help a lowbie, even at his own expense. Here I was berating one for no real reason. I changed my tune after that, and now I go out of my way to help new people to the game. If someone asks a question in Global Trade chat, amongst the myriad of rude and inaccurate answers, I always whisper them the right one. It's the least I can do.
So here's a shout out to you Guga, level 60 Gnome Warrior from Jubei'thos. I remember you, and I appreciate what you did for a lost kid.