the anime Gantz is really bizarre. It's 26 episodes and its a bit different from the general base of animes out there. there are a lot of violent scenes as well as some nudity/sex. Watch at your own risk and don't expect happy thoughts. It leaves you with the expression, ''wtf?''. Nonetheless I liked it

This is a really good show, but I'd say the bizarre factor is just above par as far as anime is concerned.

Wise Blood is a pretty bizarre novel now that I think of it.

If you've never watched Angel's Egg... well, I dunno. I consider it bizarre, but maybe that's just me. I also didn't like it, but apparently some people did so maybe you will, too? (Anime Recommendation Database says you might like these things as well.)

The manga about the spirals (someone mentioned that?) is Uzumaki, I believe (no relation to Naruto, of course). I've never read it, but I've heard it was pretty trippy, very bizarre, and somewhat nightmare-fuelish. You could probably find it at Onemanga.com or something.

Also maybe 20th Century Boys, or if you don't mind a mildly shounen flavor (and some graphic stuff!) perhaps MPD Psycho. And Akira, if you haven't seen that. Tends toward pretty crazy in the last ten minutes or so. I'm probably just mentioning that last one because we had to watch it as part of my class this week (on anime auteurs, haha).

Also, I know it's kind of "MAIN STREAM" but the only Anime I really like is Paranoia Agent. It's pretty nuts.

It's directed by Satoshi Kon, who also does some other strange works that you might be interested in. Paprika and maybe Perfect Blue (haven't seen it, but heard it's good). Actually, certain TvTropes might help you out in your search. I say "might" because you never know what you might find with TvTropes.

Also maybe not nearly bizarre enough for this topic, but I Heart Huckabees was pretty what-the-fuck at some moments.

killer 7 for ps2/gamecube (and wii)