De-lurking to post a challenge.  7 Days only ran for three seasons, but it has so much potential to be crossed over with other series! Especially Stargate, either SG-1 or Atlantis. I've been looking for crossovers between these series and have only found one, oddly enough, despite the fact that there is so much fun that could be had sending Frank Parker off to interact with folks in the Stargate program. I would especially like to see Frank Parker sent back to make a certain event not happen in the SG-1 episode "Heroes", but I'd greatly enjoy seeing any crossovers with 7 Days. Here are a few other ideas/plot bunnies.

NCIS - Gibbs' team is sent in to investigate some of the mayhem Frank Parker causes when he backsteps to fix something to do with the Navy or Marine Corps.  This could also work with JAG.
The Pretender - Frank Parker runs into Ms. Parker when he is sent on a backstep to fix one of the Center's blunders. Jarod winds up saving them both.
The West Wing - President Bartlett is briefed on not one, but two secret projects that belong in science fiction movies (the SGC and Project Backstep).
Stargate - Any number of scenarios go sideways, prompting the President to initiate a backstep and send Frank Parker in to warn/help the folks at the SGC/Atlantis.
The Sentinal - Detective Ellison senses the sphere landing near Cascade and goes to investigate, finding an unconscious Frank Parker and what looks to be some strange sort of geodesic sphere in a shallow impact crater.

The list goes on because the potential here is endless.