Batmite wrote:
  It would be pretty easy for Marvel to collect a complete "The Cat / Tigra" stories, most of it has already been collected and recolored.

Already reprinted:
"The Cat" full series reprinted in Women of Marvel Omnibus, Marvel First
MTU #8 , reprinted in the MTU MMs, 
The GS Creatures #1  reprinted in Marvel First and Women of Marvel
Marvel Premiere #42 reprinted in Women of Marvel
Monsters Unleashed #10 reprinted in Marvel First
Not reprinted
Marvel Chillers #3-7
There's also a neat little What If? backup by Roger Stern and Steve Ditko that provides an origin for the "Cat People" that would fit neatly into this volume.