Keyrow.com: Using this tool plus Google's keyword selection tool, you have 2 key resources you'll need to map out your SE traffic strategy. Do you shoot for low hanging fruit? Do you establish a foundation and, as Matt Cutts says, "roll up" to larger terms? Either way, it's a good way to get a snapshot of which words your website currently ranks and how much estimated search volume those words bring in. This will help you finetune your backlink and content strategy
Enjoy!
http://www.keyrow.com (NOTE: It's not as accurate as it can be but it's accurate enough
)
and
https://adwords.google.com/select/KeywordToolExternal