[Poindexter]

I can imagine elves, dwarves, and orks of european, asian, arabic, hispanic, and african descent, and what they'd look like, but some some reason, trolls just kinda seem like trolls and i have a hard time imagining the way nordic/germanic trolls look different from say, mexican trolls.

anyone got links to any good pics to help my brainbox out?

[SmilinIrish]

Skin coloration could vary in shade.  Location and arrangement of calcium deposits.  Shape, size and texture of horns.  totally possible to have differences in shape of eyes, mouth, and nose. 

[Crimsondude]

The B&W art hasn't been super in differentiating them by race, but there are African and Asian trolls in Cyberpirates and an African troll in Prime Runners.

Your best best is to search DeviantArt or tumblr. Lots of non-caucasian SR character art there.

[Angelone]

I feel the Troll metatypes are the most varied. In Greece you get Minotaurs, Sweden? you get Giants, elsewhere you get Cyclopes. Granted those aren't vanilla trolls, but still neat imo.

More on topic, I seem to remember them having a wide range of pigmentation open to them, but it's not backed up by the 5th ed. core book.

[MijRai]

I like to change up my trolls with some of the methods others have already mentioned; skin color (obviously), eyes (epicanthal folds for Asian trolls, not to mention color), hair color/style/texture (Disco Troll with a foot tall Afro, anybody?), horns (I love using this for differences; give the Native American troll Bison-esque or bighorn horns, African trolls water-buffalo or oryx style, the Caucasians goat or cattle, etc.), as well as stuff that suits their culture.  I mean, the Japanese troll with his hair tied back, covered in traditional bamboo sliver-style tattoos, proudly showing off an entire family tree leading back to a famous daimyo with these for horns; http://www.australianwagyuforum.com.au/images/Bloodlines%20-%20tajima%20gyu.jpg is much more evocative than 'he's Asian, and a troll'.