Gidget to Medium

The New Gidget was a sequel series to the original Gidget after 20 years

Gidget and her family went on a cruise on The New Gidget and ended up on Gillian's Island.

Meego (who was an alien) tried to contact his mother on the home planet by phone and instead the phone connected with Gilligan, Mary Ann and the Professor on Gillian's Island

Family Matters' Urkel appeared in the first two episodes of Meego.

The family from Step by Step was in the middle of a barbeque outside when Urkel from Family Matters came (literally) crashing in on the jetpack he had built on the last episode of Family Matters.

Boy Meets World and Step by Step both had episodes at Disney World and whiel in Disney World Eric from Boy Meets World met Dana from Step by Step.

Sabrina the Teenage Witch also crossed over with Boy Meets World on several other occasions.

Sabrina from Sabrina the Teenage Witch visited Cher from Clueless in the episode "Mr. Wright."

Hakeem and Niecy from Moesha went to the prom with Cher and Sean from Clueless.

The Parkers was a spinoff of Moesha

The Hughleys crossed over with The Parkers.

The Drew Carey Show's Mimi appeared in an episode of The Hughleys

The Drew Carey Show did a cross over with Coach.

Newhart's Larry, Darryl and Darryl squatted in Coach's Hayden and Christine's home

The Bob Newhart Show's Bob Hartley woke up after dreaming the entire series Newhart during Newhart's finale.

The Bob Newhart Show's Elliot Carlin visited the psych ward at St Elsewhere's St Eligius Hospital.

An episode of Crossing Jordan featured a priest from St. Eligius Church in Boston. St. Elsewhere was set at St Eligius Hospital in Boston

Las Vegas' Danny McCoy and Sam Marquez took a plane to Boston. While in flight a guy on the plane died causing a crossover with Crossing Jordan.

Characters from Medium visited the Monticito Casino from Las Vegas