Couple more I just though of.
Shakugan no Shana: It is about a high school kid who one day gets drawn into a battle between a "Flame Haze" who is a high school aged girl and a creature who devours the souls of the living. She informs him that he is a "Torch", a temporary soul, and that his real self is already dead. He joins her in her battles against the creatures and the other Flame Hazes. Sold show with two seasons so far and a likely third season to come at some point. Lots of action with a good amount of comedy and romance tossed in. Shana, the title character is a great character and is voiced by my all time favorite, Rie Kugimiya.
Cowboy Bebop Not a long series, but a must see. You probably have already seen this, but if not, go watch it now!!! It is one of those staples that must be seen by anyone who is even slightly interested in anime. Space bounty hunters. Nuff said.
Fate/Stay Night Is about a tournament that pits magicians who summon legendary heroes from the past to battle for the holy grail where the winner gets any wish they want granted. The main character becomes a participant by accident and really just wants to end the fighting. Great action and just a hint of romance.
Zero no Tsukaima Another Rie Kugimiya tsundere role (what can I say, I love her characters) this time a mage who summons the main character from our would into a world full of magic who end up as her familiar. Typical romantic comedy with more of a focus on the comedy, but there is a fair amount of action in the 2nd and 3rd season. reminds me a bit of a more adult harry potter.
BTW, you will have to post what you end up watching and what you think of them. I like threads like this because it help me find news shows to watch and remember some good classic shows I might want to rewatch.