Anything published by Apress is worth looking at, e.g., 1) Accelerated C# 2008 by Trey Nash, and 2) Pro C# 2008 and the .NET 3.5 Platform by Troelsen (4th ed.) I also like: 3) Beginning C# 2005 by Watson, et al, pub. Wrox (there's a new edition out on C# 2008, but I haven't inspected it so won't comment) For fundamental concepts, I like: 4) Head First C# by Stellman and Greene, pub. O'Reilly For financial applications I like: 5) Computational Finance using C and C# by Levy, pub. Academic Press.