House - "The Greater Good"
Judith Scott playing 'Dana Miller' was featured in season 2 of Dexter as 'Lt. Esme Pasquale.'
Chuck - "Chuck Versus The Third Dimension"
Dominic Monaghan playing 'Tyler Martin' was, of course, 'Charlie Pace' on LOST.
Lie To Me - "A Perfect Score"
April Parker-Jones, playing 'Head Mistress Jonas,' was seen not too long ago on LOST prescribing pills to Jack Shephard
My Name Is Earl - "Randy's List Item"
Neil Hopkins played Earl's old friend 'Zeke.' You might recognize him from LOST where he place 'Liam Pace,' brother to Dominic Monaghan's 'Charlie Pace' in flashbacks.
Smallville - "Requiem"
Chris Gauthier playing 'Winslow Schott' aka Toyman first showed up on another CW show, Supernatural, as 'Ronald Reznick' who tried to help Sam and Dean but got killed and then showed up in a later episode as a vengeful spirit.