People will often say Hollywood is hard up for ideas with all the remakes and unnecessary sequels/prequels/reboots but one could definitely argue that television has had a rougher go of it. There are enough crappy shows out there that producers will want a sure thing, "Hey! That movie was good! Let's make a it show! Yay!" There have been some successes for sure, biggies like MASH, Buffy, Stargate, The Odd Couple, Young Indiana Jones was even a decent show. I think some people even like the Terminator Sarah Connor show. There have a been a ton really. But check out this small sampling of ridiculous and short lived small screen spin offs, some of which i admittedly tuned in for...
Uncle Buck (1990)
Delta House (Animal House) (1979)
Honey I Shrunk the Kids (1997)
Harry and the Hendersons (1991)
Ferris Bueller (1990)
Police Academy (1997)
Here's a great glimpse into 15 TV shows that almost were, including The Jerk, Revenge of the Nerds, Fargo and Driving Miss Daisy!
Revenge of the Nerds Pilot
And yes, there was even a Poltergeist tv series.