I'm thinking about IT freelancing. What kinds of tools should I think about? So far I have Google calendar, a couple of IDEs for dev work and a bunch of communication options like Skype. What I need is more business tools and other things I have not thought about.
You are so putting the cart before the horse. The first thing you will need is a customer. Your customer will require something done. You can then consider what tools you need to get that job done. IT is too broad a topic, you could be laying cables for all I know.
To get a customer you will need a telephone and a business card (perhaps). For an online customer you will probably need a website, but a profile page would do on LinkedIn or FB or wherever. Your website could just be a blogspot blog for instance. On most job sites they give you a profile page to fill in anyway.
References are good, get three written ones you can show people on or offline, which can be called and are happy to say how nice and reliable or skilled you are.
Anything else you build up as and when you need it. Need to send an invoice, look into invoice programs or knock something up on Excel or Open Office. Need a todo list, use any online todo lists, need a calendar, use any online calendar, need a project management tool, use any online project management tools you want. None of this matters without a customer. You will not get a customer until you approach people. So the only tools you need initially are the things that prove you can do what you say you can, that your are honest and trustworthy.
Everything else you can sort out later, as and when you need it.