Don't let the playful, cartoonish cover fool you. Superpowers (David J. Schwartz, 2008) is a dark story. Not that it's relentlessly depressing or lacks light and humor, but the ending is dark and deliberately unresolved. (I warn because I'm glad I was warned myself.)
In the interests of full disclosure, I know the author, at least in the "know from the internets" sense. Knowing an author biases me enough that I'll try a genre I wouldn't otherwise read (as was the case here) and will keep reading for a chapter or so longer than I otherwise would to give it a good chance (which wasn't necessary here, as I liked it from the beginning).
In the spring of 2001, five college students in Madison, WI wake up from getting drunk on homebrew on an odd, stormy night to discover that they have superpowers--one with telepathy, one superspeed, one flight, one superstrength, and the fifth invisibility. After some discussion, they band together to fight crime, only to discover that it's not as easy to use their powers wisely as they might've hoped. The story dovetails with the actual events of 2001 (though not in any corny way where the heroes anticipate and try to prevent 9/11 or anything), which adds to the message about power and truth.
It's not a perfect book, but it's a solid debut that kept me turning pages in a genre I wouldn't normally read.