Current Status (10/30/10): Someone at dA correctly identified all ten characters! ^o^
The answers are as follows (these names would have been sufficient):
1) Hakkai from Saiyuki
2) Tidus from Final Fantasy X
3) Jin from Xenosaga
4) Allen from Tenkuu no Escaflowne/High-Flying Escaflowne (or just Escaflowne)
5) Kyoya from Ouran High School Host Club
6) The Count (of Monte Cristo) from Gankutsuou
7) Sai from Hikaru no Go (does this one even have an English title?)
8) Kilik from Soul Calibur
9) Vash from Trigun
10) Spike from Cowboy Bebop
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Edit: I changed the costume of #3 to something else he also wears. Hopefully it's a little more recognizable/unique than just a standard Japanese outfit. ^^
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I decided that the series that #9 and #10 are from were too obscure, as no one seemed to know them, at least not publicly. I've replaced them with characters that I'm sure a lot more people will know. (Good thing I have so many favorites! >o<) The answers for the original two are Marron from Bakuretsu Hunter/Sorcerer Hunters and Tsuzuki from Yami no Matsuei/Descendants of the Dark, respectively. I've left the original meme up too for you to look if you want. (Light seemed to be a popular guess for Tsuzuki. ^^ But the hair is different!)
Also, for the free sketch commission, you can note me at dA with your answers if you think you know at least 8 of these guys! I'm still going to take quantity over quickness, so if "A" gets 8 correct and "B" later gets 9 correct, "B" will still win. But if everyone gets the same number of characters correct, whoever noted me first will get it. I will run this for a week (from now) or until someone gets all 10, whichever comes first. ^^ BTW, if you get some wrong, you can still submit new guesses; there's no penalty for misses. Oh, and don't forget, I need both the character name and the title of the anime/game he's from for each!
You're welcome to participate here at TheO, but you're going to have to note me at dA for it. I was going to accept PMs here as well until I realized that messages here don't have a timestamp! >_< So if you want to try to answer, you can note me from my dA page (once you're logged in...): http://kagaminoir.deviantart.com
I'll post all of the answers once this is done, of course. ^^