What library functionality would you most like to see in D?

[Lutger Blijdestijn]

streams and network programming is most desirable, this also impacts other 
libraries. 

Another big one is async programming. Some kind of unified, higher level 
framework to deal with this could be a huge help - it's a hard problem.

It's interesting to see that in .NET a lot of new stuff concerning async 
programming is coming out, suggesting that the (many) existing patterns are 
considered inadequate. In C# 5, async operations will be a language level 
feature with the async/await keywords. There is also the reactive extensions 
library for async streams: http://msdn.microsoft.com/en-us/data/gg577609. 
Most interesting about this one is how easy it is to compose async 
operations.