If you like the weird wonderful world of Harry Potter, then you might enjoy another Harry series, one that's written for adults:  THE DRESDEN FILES.  It's main character, Harry Blackstone Copperfield Dresden, is the only Yellow Pages-advertising practicing wizard in Chicago.  As such, he attracts the attention of both the regular and supernatural world, and usually not for the better.  When he's not fighting off faeries, werewolves or vampires, he's got the Chicago underworld trying to use his talents for their own nefarious purposes.

So far there are 10 books in the series by Jim Butcher, with more great reading on the way:

STORM FRONT
FOOL MOON
GRAVE PERIL
SUMMER KNIGHT
DEATH MASKS
BLOOD RITES
DEAD BEAT
PROVEN GUILTY
WHITE NIGHT
SMALL FAVOR