There's one awesome and totally free resource I've come to know recently. It's from twitter bootstrap. It's called http://fontawesome.io/3.2.1/cheatsheet/
Now, according to them, "Font Awesome is fully open source and is GPL compatible. You can use it for commercial projects, open source projects, or really just about whatever you want."
Plus when you design using icons from font awesome, the developers could use the same icons and you design could be in sync.
By the way, about your ideas:
1) About - You could probably use an info icon (an "i" in small caps) or a group of people
2) Resources - A stack of anything your site is related to. A stack of books, stack of toys..anything..
3) Donate - Probably a hand giving and another receiving.