Simply my attempt on creating a tree.

The LuxRender materials and the leaf texture are included, the trunk texture was painted in texture paint mode (after this great tutorial: http://vimeo.com/27038995), but it is originally from cgtextures.com so I can't include it. Just grab a texture (I used this one: http://cgtextures.com/login.php?&texid=10060&destination=texview.php?id=10060&PHPSESSID=amst6hnv14h0t1mv5rfslsrbt4) and paint it on the trunk, it's not that difficult ;)

Ah, by the way, this is a high-quality and high-poly tree :) (82,000 Faces)