Last summer, undrafted rookie Greg Milhouse was one of the early stories at Giants training camp.
The defensive tackle out of Campbell University (the Fighting Camels!) briefly worked as the first-team defensive tackle while Damon "Snacks" Harrison was playing it cautious with a swollen knee on the PUP list. Harrison eventually returned, though, and Milhouse's push slowed. He was eventually included in the Giants' first wave of cuts and hasn't caught on with another team since.
Josh Banks would like to do the same (plus more) this preseason.