Rotoworld has an article up discussing possible non-tenders, and here is who they have in their "likely" category:
C Johnny Estrada (Mets), OF Craig Monroe (Twins), INF Felipe Lopez (Nationals), 3B Morgan Ensberg (Padres), OF Emil Brown (Royals), 1B Ben Broussard (Mariners), OF Kevin Mench (Brewers), C Miguel Olivo (Marlins), LHP Mark Hendrickson (Dodgers), LHP Horacio Ramirez (Mariners), LHP Neal Cotts (Cubs), OF Jason Lane (Padres), OF Cory Sullivan (Rockies), RHP Brendan Donnelly (Red Sox), LHP John Parrish (Mariners), LHP Wilfredo Ledezma (Padres), RHP Greg Aquino (Brewers), RHP Seth McClung (Brewers), RHP Grant Balfour (Rays), RHP Dave Borkowski (Astros), C Eric Munson (Brewers), RHP Brandon Duckworth (Royals), RHP Ryan Wagner (Nationals)
The two names that stand out to me the most there are Johnny Estrada and Morgan Ensberg.
I have no idea if the Reds are looking for a catcher (probably not), but I think Estrada might be a decent idea if they don't think Dave Ross can improve on his 2007.
But Ensberg is an even better idea I think. He would give the Reds insurance in the event of an Edwin Encarnacion trade, and even if that doesn't happen I think he'd make an awesome platoon partner with Scott Hatteberg. He's hit .284/.406/.530 in his career vs. left handers, which would make for a great first baseman when combined with the lefthanded Hatteberg.
This is assuming the Reds will be dealing Votto at some point. If the Reds are planning on holding on to both Votto and EdE then Ensberg wouldn't make any sense. But if the Bedard trade (or anything similar) goes down it's more than likely that one of those two players would be gone, if not both, and I'm not sure the Reds could do much better than Morgan Ensberg to fill the ensuing hole.