If your starting QB is a young stud like Vince Young, Leinart, Rivers, Roethlisberger, Eli or Cutler, I'd be targeting Favre or Kitna for veteran stability. If I can't get either of them, I'd see what it would take to get Delhomme. I'm tempted to say Trent Green as it still looks like he'll end up in Miami, but I think his useful years are behind him. I'm also tempted to say Damon Huard, but I think the Chiefs' passing offense has little chance of matching the production of previous years.
I think Ahman Green is once again the perfect RB to fill this need. I used him in exactly this fashion with a trade last summer, and then I traded him away at the end of the year once I was finished with him. But he can definitely be useful on a week-to-week basis as you're waiting for a Cadillac or DeAngelo Williams to fulfill their potential. I'm hesitant to say Jamal Lewis because it's clear that he doesn't have much left in the tank and Cleveland hasn't been kind to starting RBs, but his value is so low right now that you could probably swipe him on the cheap and hope the Browns don't address their RB situation in the draft. If Jamal is to be believed, he's healthier now than he's been in a couple of years. I don't see a huge turnaround, but he was definitely useful as a starter at times last season.
I typically stay away from older WRs unless they're still studs. If I had to name a couple to take a chance on I'd say Joe Horn can still be productive when healthy and he has a chip on his shoulder this year. Galloway is another one who still looks like he has something left. Muhsin Muhammad and Derrick Mason both look like they were passed as #1 options last year, and both have talented 3rd WRs (Bradley & D.Williams) forcing their way into more playing time in '07. I'll be interested to see what happens with Moulds this offseason.