Pretty much what the title says. Surprised there hasn't been another thread like this actually. I guess this is an anime recommendation thread too?
I'm currently watching:
Soul Eater - An anime about two types of people, weapons and meisters (the weapons are people but possess the ability to transform into a weapon) The main two protagonists are Soul (Weapon) and Maka (Meister) their main goal is to have soul eat 100 kishin souls and one soul of a witch so he may become a Death Scythe. (available in eng sub and dub)
Note: Do not be put off by the art style in Death City.
Accel World - An anime about a fighting mmo accessed via neuro linkers (collars which act like a computer) where you must collect enough 'burst points' to achieve level 10. These burst points allow you to freeze time in real life and have advantages ingame. When you run out of burst points, the game uninstalls and is unable to reinstall. The main protagonist, Haru, is picked out in his school by the most popular girl for his gaming prowess and she asks him to help her achieve level 10. (available in eng sub only)
I highly recommend them both