For the past few years I have been finding 'one-liners' on 'other' minor alien races from all of the 40K codices & books and developing them into their own Index Xenos articles (and then modeling them into 40K 'alternate' armies - with extensive modeling blogs). I thought that they would make good material for 'alternate aliens' for Rogue Traders and decided to share them. Most of the work is mine - and where I have copied stuff from GW it is meant as a tribute only. I've already posted them in the Rogue Trader Forum and so I won't repost them here as well.
I hope they give you all many ideas for your games.
http://www.fantasyflightgames.com/edge_foros_discusion.asp?efid=158&efcid=3&efidt=282950