First I'd like to start with a notorious UT player who went by the name of "LAMP", this was several years ago. He was running an aimbot hack where he managed to keep the entire opposing team at bay by constantly headshotting all of them within seconds of their spawning (sometimes getting multiple headshots quicker than in a second) despite being on the other end of the map.

It was mildly amusing at first, but quickly irritating and you just knew things would suck when you'd see him enter a match. I've never seen a group of people become so pissed off they literally sat out through a series of matches until the jackass finally left.

Not long after more and more servers started running the "Pure" mod where your install was essentially verified to not include any hacks or exploits, and I'm pretty sure Pure was added to UT today (though there are of course new exploits).

Any experiences like this?

I did have some fun once on Deus Ex multiplayer when some members of my team starting being complete douche bags. I didn't run a hack, I logged back in as Timmy Keller and started blowing them away *lol*. I remember grabbing a flamethrower off the wall and one of the team members saying "Don't" before I set him ablaze. Within minutes the team started attacking me and inadvertently damaging each other.. soon the whole team was more focused on killing each other with whatever weapons they could grab.

Yea, normally I was the asshole doing it. Haha. I used to do whacky stuff like wallhacks for shits n giggles. Id just line up my shots and wait till it was "legit" and fire. Id get accused and a friend of mine would just start defending me and hyping me up that im in that big tourney coming up.
this was in HL1 cstrike usually so we did the other glitch to have 2 people on 1 key so when you got banned/kicked it kicked 1 of yous and couldnt kick the other one saying Won id already banned.
And in quake1 tf I used to go into teamkill games named Hitler and just spy gas the respawn room, Usually id have a friend on other team named hitIer doing the same thing.
But i do recall once playing day of defeat and someone had a crazy speed hack so theyd go prone and basically be crawling around crazy fast and instant killing everyone with the knife.
But I remember a time or 2 with some new anti hack stuff released and having an xploit and hacking just because it "couldnt" be done.

You're the reason we can't have nice things.

I don't think my online cheating exploits ever went beyond duping items in Diablo...

Bah, when I say I did it, it was for laughs maybe a couple hours total in my years.
Anything competitive like starcraft n what not, I never did it.
Diablo duping I did a couple times and maphack, but only the cpu was hurt there.

Starcraft lol I remember playing a 3v3 once while one of our clan members was on the other team we played half way and he turned on them as well lol

I've come up against hackers a lot in various games, MW2, TF2 (rare), and COD:BO lately.

Personally I haven't hacked many games. I did run a texture hack in MW2 for a few weeks but I went back to vanilla after a while since it wasn't kosher. I have used glitches to grief people in game, but only for fun.

here's some of my greifing exploits on youtube:

http://www.youtube.com/watch?v=bpXNVD9rkoc
http://www.youtube.com/watch?v=qGZTShWOsRk
http://www.youtube.com/watch?v=-xq6mvCf-T8

Im not even clicking em, but i will guess those were them amusing left 4 deads? hah