I feel I have to mention the awesomeness that is Ravelry. A brief description is that it is sort of social networking for knitters, and yet, and yet it is soooo much more.
It has an awesome resource for browsing patterns and seeing what other people have done with said patterns, thus allowing you to see what different types of wool and things can be done with a pattern!
I can browse yarns and easily find out what weight a yarn is considered as and thus know if i’m using something that works as a suitable replacement. Which is sooo awesome especially when your just starting out and don’t really understand much at all!
Plus there’s handy forums to go to if I need help.
It’s all so nicely packaged together. 🙂 I love it!