You have many options to do with your money. - Spend it on yourself. - Invest in Paid to Click website NeoBux.com (Read about it; It's not scam) - Create a website, offer a service or useful e-Book and sell it. - Buy some beer. - Save it up (pretty useless).
Just keep it with you until you reached 1000 mark and then plan something big. 100 is very less I think.
start a site at hostgator.com i u know programming language and earn more form $100 and buy iphone 3G, sony cybershot, apple macbook and much more you want, but at first you want to make you site popular with that $100
See what is getting all the IM gurus are talking. See what product they are promoting (something in the internet marketing) and buy it.
buy PR3+ domain, build a blog on it, and submit ur site to paid-to-post program like sponsoredreviews, payperpost, blogsvertise, etc.