There were a lot of good players who went undrafted, and Dan Pompei writes for National Football Post about a number of players to keep an eye on. Here's the two that he mentions with contracts from the Jets:
WR—Zach Rogers, Jets. He got lost in the shuffle at Tennessee, but he can run and is competitive. He could blossom in the NFL.Rogers is a very consistent receiver, but needs other targets around him to flourish. Miles also has potential, but will need to become technically more sound to hit the field with the defense on Sundays. With no drafted players at the receiver or safety spot this year, Rogers and Miles might stand a good shot at securing a roster spot, but it's going to come down to special teams first and foremost for these undrafted rookies.
S—Rontez Miles, Jets. He probably would have been drafted if not for running a 4.59 40 yard dash at the combine. After that, there were questions about whether or not Miles was a strong safety only.