zaxxon, mainly there arent much tutorials etc available....
most of the time you can search for basic PC infos & source codes (asm, pascal, c) on the web and there are a lot of tutorials for many effects same as you have mentioned...
the tricky part is then how to transfer that into our lovely 8bit machine and do it fast... once you know how to prepare the desired lookup tables you can transfer the concept of an effect...
f.e. transparency (alpha blending), zoom rotator, water/fire, warping, tunnel, wolf clone, 3d stuff, blurr, bump mapping, etc. etc. etc are all well known from PC/Amiga so you find tutorials there...(hurray google)
check out my links:
here is my source code of really unreal intro with twirling / burning lines:
(even the algorithm is being described...):
http://www.stud.uni-...ari8/demos.html
1st start regarding the so called "GTIA modes" (80x60)
http://www.s-direktn..._nadj/gtia.html
but nowadays you'll use "mode9++":
http://www.s-direktn...dj/mode9 .html
unfortunalty a lot of demos are written in poland so a lot of tutorials are not in english... sad but true. you'll can check & search the net for this atari disc based magazines:
mega magazine from freddy offenga (asm tutorials) in english
barry mag from shadows (? not sure about that...polsih)
abbuc magazines (german)
energy fancine (by taquart...polish)
and a lot of other stuff like atari 3d stuff is available on the net as well...as far as i can remember satantronic has published their 3d thorus demo incl. source code... (not to mention of course the complete source code of numen demo...

)
i had many inspirations from amiga & PC demos, tutorials AND c64... get the "the fridge"
http://www.ffd2.com/fridge/ and read through the heavily rewarded and usefull "c= hacking issues".
of couse you can not transfer 1:1 c64 code but the algorithms and concepts can be ported and the c hacking issues are in english...
f.e. the "fast multiply algorithms" method is used in several demos on atari (i haven't used that in my really unreal intro... that's why you have a 2 minutes precalculation time with the TQA logo at the beginning......sorry i am not a math guy...

)
i am sure dracon can add a lot more here and even our c64 guys like TMR.