Several, of course. I had a friend who did his own version of the Dark Tower series combined with Lord Of The Rings. I came in about half way through the campaign, playing a wizard turned dwarf (due to his lecherousness, of course).

Other than that, there was a Supers run I liked, and I have a Traveller variant that I'm trying to get my current group into after our Shadowrun characters die.

.
. Back in the days of BBS' (I am dating myself here), yes pre-internet, I was part of af a campaign involving a post cataclysm event. Our team was one of many that volunteered to be part of a secret society to 'preserve civilization'. We agreed to go into stasis as things began to crumble, and trust the base computer to revive us when the smoke cleared, so to speak.
.
. I played a special forces warrior with a chip on my shoulder, a penchant for alcohol and tobacco (Jack Daniels and Copenhagen) and a weakness for females.
.
. we were revived and started looking for survivors, and to discover what the cause of the disaster was.
.
. The game unravelled (as many e-mail games did/do) before we discovered the details. But the GM was kind to share the details. The earth had been invaded by alien forces interested in strip mining us for resources (mineral and labor, food). They started by knocking out all radio communication, anywhere.
.
. There was an interstellar empire, that protected worlds from this, within its borders, but the empire was not yet knowing we existed, so the aliens that discovered us were taking all they could before the empire extended to incorporate us.
.