Bing Webmaster Toolbox: Oh yeah, remember that other search engine? Yes that’s right Bing has a whole collection of tools of their own, including keyword tools. The data will be taken from Bing itself, which means that you should be able to make relative assumptions about keyword popularity. because lets face it, Bing users aren’t that different than Google’s.
Long Tail Pro is a keyword research tool that helps you quickly find low competition keywords for your website. In particular, the tool is built for people doing SEO (search engine optimization) as opposed to people doing paid ads (Google Adwords PPC). I'm sure there are some advertisers that use the tool for paid ad keyword research, but the tool was built for SEO keyword research.