Oh lord, I don't read much Wimseyfic so I'd be hard pressed. adina_atl wrote a lovely crossover with Wimsey and Wooster, which you can understand even if you haven't read Chesterton:

http://www.livejournal.com/users/adina_atl/58365.html

(that's the end, but it has links to the other three chapters).

Other than that I can't think of any Wimsey writers off the top of my head. We're a really tiny group in general. DLS is a hard author to fic :D