HI O. --
Boy, did you ask at the right time. I just finished submitting a proposal for a $1.75M grant for a 5 year research project.
There are lots of places to look, but start both at www.grants.gov and look and see if any of the available grants apply to the type of work you are doing and then go to www.sba.gov and do the same.
Grants.gov is huge. Applying for a grant is a huge project, but not impossible. Besides just submitting a proposal, you need to register, which takes up to three weeks. Click on the Getting Started button on Grants.gov, and it will walk you through the process. If you find what they call a 'funding opportunity' (a grant you want to apply for), get crackin' on the registration!
Each funding agency (NIH, Department of Ed, etc.) has their own requirements and format you need to follow. Once you find an opportunity that works, download all of the instructions, the funding program, etc., and pour yourself a glass of wine and start reading. Once you have a handle on what to do, start writing up the proposal, and follow the directions for submission.
It's an enormous amount of work, especially the first time, but there are lots of opportunities, so GO FOR IT!
Hope this helps,
J.