There is no cheating in World of Tanks, as all calculations are done server-side.

I've played e.g. TeamFortress Classic for like a decade, and I can't recall if I've ever seen a confirmed cheater. Sometimes I've seen some people blaming someone else in the server of cheating (like a sniper who is able to shoot him in the head continously), but I think that moaner probably just had such a big head that it was hard to miss.

So I presume that at least Valve online games have pretty good measures to keep cheaters away, at least they haven't been a nuisance to me. TeamFortress Classic, TeamFortress 2 etc. But I could be wrong of course.

In the original Quake TeamFortress it was different, I left the game in disgust as the servers were full of cheaters running four times faster than you etc. I think back then the Quake servers tried to rely on PunkBuster to curb cheaters.

I was out browsing the other day and I noticed an action-replay style disc thingy for Xbox 360; think it made a noise about having cheats or hacks for CoD or something like that. This wasn't in an independent store, but in a branch of GAME.

It's a shame, it really is; it's not fun for anyone, since when is winning through no effort of any enjoyment past the first, maybe second time?

Reminds me of those people who uses hacks or glitches to max out their single-player game and then brag about it. Great, you've missed out on hours of enjoyment, good for you.
Red Orchestra is an example of that, there's servers on it that are Valve-approved or something like that and they detect cheaters and you can vote/kick someone who you suspect is cheating. DRM has some advantages...

Turn based games require patience, which something 95% of cheaters, especially the younger ones simply dont posses.

Then ofcourse, many turn based games are far more pure skill based, when autoaims and such simply do not help. So for those who just want to cheat and ruin other people's games, fps and mmo are simply more easy than forexample Go is all about skill, not slightest sliver of chance and where all the moves are visible to both players.

Blood Bowl has dice, but as far as I know those are on the server and you cant touch em.

Thinking about TB's the most obvious thing to cheat at would be visibility, in games like civilization - not sure if that can be made though. Stuff like cheating resources or so would propably we visible post game atleast, if the game supports playback - like many TB's do -> quick ban for the cheater.

Anyways, TB's are often take far more seriously by the players than FPS's as in FPS its easy to just change server - but to a TB you often have to invest far more time, atleast if the game involves more than 2 players (civ type games for example).