I am so completely spoiled by Peter Blum's Data Entry Suite. His ASP.NET data entry and validation controls are so awesome and they just work. But this month I'm doing a lot of WinForm development, and so I can't use them. I've poked around a bit looking for something comparable to DES for WinForm development, but so far I haven't found anything as good. Plus I'm not enthusiastic about trying to wrap my head around something new, especially since the ones I've found so far are pretty pricey.
This was the closest thing I've found to something useful.