It depends on where you live and what you intend to do. If your goal is to create a one person operation you probably aren't eligible as most grants either expressly or implicitly require that you add jobs. Your best bet for locating grants in your area is to ask someone at the local incubator or check an online source as identified by Martin Omansky. One thing to avoid is paying for a list of available grants as this information is freely available.
Before you apply, you should arrange to meet with the granting agency to learn three things:
1. Do you qualify?
2. Are they accepting applications? Some groups have specific intake dates that you have to work around while others may be fully expended for the current fiscal year.
3. What do they want to see in your proposal? Every agency is different and the level of information required is often dependent on the reviewer. If they publish a list of grant recipients call one or two and ask what they did. As part of this question, find out how much cash you need to put up. Most grants use some form of matching system. If you are seeking a grant because you have no cash, they aren't an answer.
One piece of advice, only use grants to top up funding. The process for getting a grant is often long and may not suit the timing of your business. You should also consider the grant provider may require you to do things that aren't in the best interest of your business. This can often result in the business losing focus and growing based on the granting agency's requirements rather than solid business reasons. Whatever you do, do not become addicted to grants as research and experience shows this is not a successful way to grow a business.