I briefly mentioned this in the GM thread, but I kind of like this idea:
Up through 2014, Brandon Fusco was looking like a late round gem for the Vikings and developed into a pretty good starting guard. Since then, he got paid and things went downhill. Now he's on the street as a roster cut. He's 28.
Given that he is coming off a couple of pretty bad seasons, he should be cheap. You might get him without any guaranteed money (incentives could be a good option). He was cut, so it would be irrelevant to the comp. pick formula. Plus, our OL development and coaching is among the league's best whereas the Vikings are among the worst in that area.
Bring him in, see if he has anything in camp. Best case scenario, he regains his starter quality play and you have a huge bargain. Worst case scenario, he truly does suck for good and you cut him without being out much (or perhaps anything).