This is a pretty big list for one post, make sure to check them all out though. These are pretty much my go to links to enjoy with some good music. Here is a board with a few awesome, trippy, gifs - http://www.pinterest.com/TRCvm/movement-inspiration/
Some interesting artwork, very cool visual effects - http://www.matiklarweinart.com/artworkgallery.php
I don't really find this one very stimulating, but some people might. It's a multicoloured oil slick looking, interactive fluid simulator - http://cake23.de/turing-fluid.html
This one is awesome to look at with a different perspective, really mind boggling. 3D explorable universe - http://workshop.chromeexperiments.com/stars/
This one seems quite stark and, I dunno, simple, to begin with. But the longer you look at it, the more absorbed into it you become. Some Psychedelic visuals, quite enjoyable IMO - http://iacopoapps.appspot.com/hopalongwebgl/
This is a sure highlight for me, always very fun. Online multiplayer music making - http://labs.dinahmoe.com/plink/
A thread of geometric and abstract wallpapers, very fun to have a look through - http://imgur.com/a/4rn0o
Another that never had a great effect on me, but some may find it fun. A time dilation, webcam using, self video thing - http://william.hoza.us/timewarp/
Another that, at first, seems quite basic. But it's kind of like music. You look (listen in musics case) at it for a while, and your thoughts just get carried away into it. Just a 3D visualisation of some dots - http://www.unid.me/demo/vectorstream/
Some freaky 3D GIFs - http://imgur.com/a/iGNlP
A plain old kaleidoscope, another that I didn't care for too much - http://darkpsychedelic.ru/FV_17.html
Another simple, yet fun one. A rotating canvas that you can draw spirals on, get a cool tunnelling effect - http://codepen.io/jackrugile/full/DGenc
This is probably one of my favourites, create mirrored, multi axis art. Very fun under any circumstances - http://weavesilk.com/
This one is just a blog, but has consistently amazing imagery posted to it. Another that is great to check out under any circumstances - http://butdoesitfloat.com/
