Joe Mauer (.340/.394/.448 v R) and Miguel Olivo (.278/.316/.694 v L) have been a terrific platoon at Kaufmann for me. Another very good platoon has been Willie Tavares (.308/.336/.370 v R) and Eric Bruntlett (.281/.361/.531 v L) in CF, also in Kaufmann.
Have also had very good success with Brian Lawrence, John Halama and Ian Snell there, although the latter two have been judiciously used.
I know a lot of people have had some tough luck with Brian Roberts, but he's been solid for me - .285/.378/.480 w 31 doubles, 14 HRs and 26 SBs through 108 games. Tony Clark has put up good power numbers but little else.
I know I shouldn't have expected much from him but with US Cellular and Great America in the same division, I expected a little more than .227/.334/.478 from Manny Ramirez. And Joe Nathan has been brutal, blowing 10 of 34 save opps and posting a 1.50 WHIP and 4.73 ERA.