[solipsism]

Vinge's Deepness series certainly isn't "near future" science fiction, by your definition, is it?

Anyway, give Diaspora by Greg Egan a shot. I'm not familiar with a more visionary story that challenges the most fundamental aspects of identity in so many ways. It's definitely not "near future" either, though.

[Erikun]

Egan's Permutation City is near future though, and pretty amazing that it was written in 1994 considering the topics.