Oh, and here's my personal recommendation list (anime only for now)
Anime that I've scored 10 out of 10 (ever - my scores often fall and rise while I'm comparing past anime with new anime) are bolded.
Comedy
- Lucky Star
- The Melancholy of Haruhi Suzumiya
- Gintama
- Seto no Hanayome
- Kannagi
- Hayate no Gotoku
- Detroit Metal City
- Full Metal Panic
- Azumanga Daioh
- Bokusatsu Tenshi Dokuro-chan
- Minami-ke
- Sayonara, Zetsubou Sensei
Romance
- Air
- Kanon (2006)
- Clannad/Clannad After Story [especially the second season, After Story]
- true tears
- ef - a tale of memories/melodies
- Toradora
- REC
Action (including mecha)
I'm not too big on action, but here's my list anyway
- Code Geass
- Tengen Toppa Gurren Lagann
- Darker than BLACK
- Baccano
- Shakugan no Shana
- Mobile Suit Gundam Wing [hell yeah, retro!]
- Fullmetal Alchemist
- Cowboy Bebop
- Trigun
Horror/Suspense
- Higurashi [the best horror show out there. You will **** your pants. You will **** your pants so many times that you'll run out of pants to wear.]
- Death Note
- Elfen Lied
- School Days [nice boat]
- Serial Experiments Lain
Everything Else
- Eureka Seven [the best anime ever made. It's mecha and romance fused together with a ton of awesome.]
- Mushishi
- Natsume Yuujinchou [Mushishi's little brother]
- Moyashimon
- Eve no Jikan
- Beck
- Strike Witches
- Shinigami no Ballad