There are two Project Gutenberg
language libraries on the net.
www.lib.ru is a huge archive of all sorts of russian literature, maintained by Maksim Moshkow. The content includes: Poetry and prose, as well as technical literature and science fiction, texts on history and art; both original russian, as well as translated. There are over 2 gigs of text there at the time of this writing.
Note:www.lib.ru also has some russian works of science fiction translated into english. You should be able to find them on the main index page.
www.rusf.ru is devoted to science fiction only and maintained by volunteers. Many of the newer russian sci-fi writers have their homepage there. It has a fairly large bookshelf which mirrors some of the pieces from the www.lib.ru.