Hi Aniston,
Take a look at this keyword list generator from seobook, its really simple and it makes it easy to create enormous lists of keywords:
Free Top Keyword List Generator
If the issue is brainstorming ideas for keywords (rather than creating massive lists), then you can take a look at Google's keyword suggestion tools. You can also go to clusty.com and do a search for your product. This search engine will show you "clusters" on the left hand side - these are keyword groups that are logically connected to your query, you could get good ideas from looking at them.