Although a minor part of TFA, Snap has gotten a lot of coverage in the EU's Aftermath novels and Poe Dameron comics. He's also played by Abrams frequent cast member Greg Grunberg.
http://www.theforce.net/story/front/..._IX_181752.asp
Makes me wonder if the Outer Rim allies will be involved in the plot somehow, as that's who Snap and co. were sent to look for. Curiously, the Battlefront II DLC also has Leia sending a character on a similar mission.