Achievements have done a lot of good for video games in the last few years. I know some people would disagree with that, but I guess I'll argue both ways real fast. 
 
For achievements, I like having them on my games as it gives me something to shoot for. I have squeezed more life out of games than I probably would otherwise because of achievements. I love giantbomb.com's averaging system so that I can easily go into my list and say "Wow, I barely played UFC Undisputed 2009" but then realize that I got that at a garage sale, so I don't care too much. It helps me find what I maybe should try a bit more.  
 
Farther in the opposite direction though, achievements are tools for me to identify games that I just plain don't like. Dark Sector has something like 250GS just sitting there waiting for me to finish the game, but nope. I'm not doing it. Farcry 2 is another in that league. I have found that those games are not for me. 
 
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With my disappointment at the lack of GB trophy support, and my enjoyment of achievements in 360, Steam, and blizzard games, it becomes completely surprising when a game gets my undivided attention without achievements in it for me. 
 
Recent games that have done this for me are Professor Layton and the Curious Village, Picross 3D, Mario and Luigi: Bowser's inside story, and a whole mess of Telltale games on Steam. 
 
I find it particularly odd that some of those games still have me going for 100% completion even when I really don't have anything to show for it. Sure I have very little to show in any of my gaming achievements (save maybe someone noticing a particularly rare one or something), but with Strong Bad's Cool Game for Attractive People Ep. 1, no one will ever know that I have all that stuff done. 
  
I really respect any game that can get my attention like that. I'll put up reviews of some of those eventually. The DS is the most obvious leader in my category here. For some reason I've been playing that a lot. 
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Next: My building a computer adventure! (I hope I can do that one soon.)