You may get some ideas by downloading our animation showcase. There's no
password so you can work out how the effects were done!

http://www.technologytrish.co.uk/download.html

Some example special effects in powerpoint
"Cool Powerpoint Animations"
http://www.awesomebackgrounds.com/cool-powerpoint-animations.htm

see also
PowerPoint Heaven Showcase - A promotion presentation for PowerPoint
http://pptheaven.mvps.org/animations.html

Cheers
TAJ Simmons
microsoft powerpoint mvp

awesome - powerpoint backgrounds,
http://www.awesomebackgrounds.com
free powerpoint templates, tutorials, hints, tips and more...

Here's a list of links on advanced animations which I have posted on my blog.
Check this out:
http://msmvps.com/blogs/tohlz/archive/2006/07/12/104530.aspx

I was going to steer you to some sites this morning, but I was in a hurry to
head out (to the dentist, blech).

Anyway, what I was going to say is that you may just want to spend time
studying how the existing animation effects can be used to create additional
animations you may not have even imagined. By combining effects, you can
create some really sophisticated animation in little ol' PPT.

In addition to the sites you've already been directed to, see also
http://www.tlccreative.com/ppt_tutorials.htm
http://www.pptworkbench.com/html/communication.htm
http://www.terbergdesign.com/port1.htm

and check OfficeOne animations for 50+ additional effects (which is what you
were really asking for in the first place).
http://officeone.mvps.org/anims/anims.html