I once did visit a page that had all the colours layed out with descriptions of what they are best used for. There were so many and I quickly decided filters weren't for me, and I'd stick to the 'clear' filter.
Sorry, can't find it now.
Oh hangon... I just did..
http://sciastro.net/portia/advice/filters.htm
Yeap. Still way too many there...
Roger.