Here's a list of what's left out there. I didn't include any relief pitchers that could be turned into starters, but there don't seem to be any worth mentioning anyhow. If any of these guys have already signed, my apologies. But this list certainly makes signing Edwin Jackson or trading for Gavin Floyd seem much more important now.
Javier Vazquez - Pitched 32 games with the team formerly known as Florida last year. Finished 13-11 with a 3.69 ERA. Played for the Yankees the year before, posted a 5.32 ERA. He's turning 36 in July. I'd keep going, but i'm sure you guys moved on after the words Javier Vazquez appeared.
Rich Harden - Hasn't had an ERA under 5 since 2009. Great strikeout numbers, 51 away from 1,000 career. Over a 2:1 k:bb ratio. Turned 30 in November. Pitched 15 games last year, 20 the year before. Can't prove he can pitch against the big boys. Probably the most pros out of any free agent remaining, but a long list of cons as well.
Ben Sheets - No one knows what to make of this guy. Nasty stuff when he's healthy. Pretty sure he came out of the womb injured though. 2010 only season he pitched in since 2008. Finished 4-9 with a 4.53 ERA and 2:1 K:BB ratio. Sure he might be worth a minor league contract, but I have no idea where this guy stands health-wise.
Chris Young - Read above. 6 games pitched in last 2 seasons.
Jon Garland - Pitched decently while healthy for the Dodgers last year, including a dominating complete game effort. However again, health is the main issue here. Good be the best option out of the "if he stays healthy" category though.
Brad Penny - We've already seen him once. Felt like 12 years ago. He actually finished an entire season last year with Detroit, posting an impressive...5.30 ERA. The 2007 16-4, 3.03 ERA Penny is long gone, and he's looking like he has not very much left to offer. Especially in the AL East.