If you find that any of these links are dead, please let me know at RisusRules-at-gmail-dot-com. I will do my best to keep them up today.

These sites are linked to without permission, but credit is given where and when I can establish the author.

1 Large list of optional rules by Rene.
2 Risusiverse, a wiki with a large amount of input from the Risus Group.
3 Peter Kisner has several optional rules here, includeing cross-pumping and alternate dice mechanics.
4 Home for Risus Starwars, Risus Mage: the Ascention, and Risus Vampire: the Masquerade - author Unknown.
5 Peregrine's Risus Monkey has some interesting settings.
6 Silverlode 1908 is home of some pulpish western rules - author Unknown.
7 Larry Bullock's Unearthed Risus has a character creator and conflict simulator programs.