Jonathan Adler says here the Democrats should do like was done with Judge Gregory and renominate and confirm Peter Keisler to the D.C. Circuit, citing this article by Quin Hillyer, which is also cited in this post on the Committee for Justice Blog.
Here the NRO editors suggest the same idea as to any of Bush nominees to the Fourth Circuit, including Judge Robert Conrad, Rod Rosenstein, Steve Matthews, and Judge Glen Conrad of the W.D. Va.
Somewhat more traditionally, posts here and here speculate on North Carolina Democrats who might be appointed to the long-vacant N.C. seats on the Fourth Circuit.