Toonami was pure win back in the day, DBZ, Gundam Wing, Outlaw Star, yes, even lolSailor Moon (I'll admit it, I watched it). The day they stopped Weekday Afternoon Toonami was a very sad day indeed :<
Thought for the hell of it, posting what I've seen personally and or own (either via actual DVD copies or HDD) Note, im gonna leave kiddy shit like Pokemon (LOL) out of the equation.
DBZ (You know by now, lol) (Pretty much have seen every episode from Dragonball through GT)
Sailor Moon - Let's not talk about it, lol
Gundam Wing - One of my first favorite series that Toonami had. I need to go bum the series off one of my friends again. G Gundam (which was shown later), sucked. Don't buy it. Currently watching through Gundam Seed (own 1/3 of it, need to finish collection at some point), and Gundam Seed Destiny (follow-up to Seed). Mech show
Yu Yu Hakusho - Was a decent series also, more of a darker-toned DBZ
Outlaw Star - Another favorite of mine, probably gonna go buy it at some point. Been a while since I've watched it, so can't really give a description.
Neon Genesis Evangelion - If you haven't seen this series, go watch it, Now.
Magic Knight Rayearth (one of my current faves) - An old but good series about 3 girls who are sent to another world to save it. It's an older series, but one worth watching

(Own the entire series (49 episodes - 2 seasons)
Tenchi Muyo (and the follow-up series, Tenchi In Tokyo) - Used to be on Toonami as well, own half of the first show (Tenchi Universe). Need to go watch through it again.
Azumanga Daioh - One of the funniest series out there. It's worth watching from start to finish, wish it was longer :< Highly recommended (Own

)
Inuyasha - What was said earlier is pretty much the moot point. It's really only worth watching throught the first 54 or so episodes, after that, mainly filler. (Own 1/3 of Season 1 and all of Season 2, plus 3 of the 4 movies (Movie 3 best of them imo)
Cowboy Bebop - Another must see series. Space and Cowboys, what a potent combo! One of my favorites
Trigun - Anime meets Western, 'nuff said.
Sola - (Own all the series subtitled on HDD) Decent series if your into Dramas. Have to watch through it again, before I can really say anything about it. 13 Episode series
Air TV - (Own 3/4 DVDs) Another Drama series, but a decent one. Sad ending however =(. 13 Episodes long, plus a Movie (Air in Summer Special)
Rurouni Kenshin - Samurai series that used to Air on Toonami, about Kenshin Himoura, who was a fierce soldier in a War in Japan, but is now a hero among the people. (Vauge discription). I wish this was airing again =/ Been a while since I've seen this series.
Bleach and Naruto - Not really into either, pretty explanatory tho, Never got into One Piece (never was into pirate animes anyways, plus the horrible dubbing by both 4Kids Entertainment & the people at Cartoon Network turned me off completely).
Fate/Stay Night - A friend recently introuduced me to this series about 6 people involved in a war for the Holy Grail, was actually a decent series despite its length (24 episodes)
Other than that, that's all I can remember/recall. Not good at describing series, but theres the gist of what I've seen (and some I actually own)