Gin Rummy with Jokers
Various sites (e.g., rummyculture) list rummy variants with jokers, but not Gin Rummy specifically. But the rules could be adapted directly. Suggested set of rules:


Jokers are worth 30, as in most versions of Rummikub
Discarded jokers cannot be picked up from the discard pile (optional)
Jokers can be used in sets or runs, but not to make a 5-card set (the "missing" card must be one that exists).