Can I use the icons for my websites/blogs? Sure, they were mainly designed for software application interfaces, but feel free to be creative.
I am really thankful that you made them free, how can I help you? By spreading the word about this project. Feel free to Digg it or Social Bookmark it. Buttons are on the header.
But I want to help financially. If you insist, please send the funds to xyz[at]xyz.com using paypal ;)
Are you planning to release more free icons soon? Not in the near future, but if the time and money permits, I will.