1. Horror of the Blood Monsters
2. Arachnia
3. The Dead Hate The Living
4. Stacy
5. Necromantik
6. Troma Triple B-Header volume 3
7. Troma Triple B-Header volume 1
8. Oldboy
9. Suicide Club
10. Phenomena
I saw some other good choices listed in this thread that have been added, as well.
Not sure if you have seen any of these Shadow, but it's a great list. Dead Hate The Living is a fun little zombie flick. Very low budget, but worth watching. Stacy, I'm assuming is the Attack Of The Schoolgirls film? It's another fun, if a bit confusing, zombie flick.
Necromantik is certainly unique. I haven't seen it in a few years but once was enough for me. It's not bad exactly, just.......unique.
Oldboy is a classic and the best film you have in your list. To be honest, I'd recommend moving that all the way up the list to the top. It's unbelievably good. Oh Daesu is such an awesome character and the various twists in the film are top notch.
Suicide Club is another fun Asian flick. Schoolgirls committing suicide in front of a metro train is always fun.
Phenomena is good as well. I finally got around to renting it from Netflix last year and it's a blast. Very strange film, and the killer in it is superb.