Here's a quick example off the top of my head.... (sorry for the lack of
detail about the virus)
Approximately 10% of the murine genome consists of a repetitive element
which is believed to be the remnant of an incorporated virus. The viral
genes present on this element contain some coding information which may
have been incorporated into murine genes through splicing mechanisms.
I appologize for the terrible lack of specifics, but maybe this will give
you enough to start hunting.
John C. Tilton
The Scripps Research Institute