In DM News, Andy Beal recommends that you search blogs to find the hottest keywords. There's a nice bit of logic there, and it makes sense to find bloggers who influence your industry and keep up with their posts.
The underlying premise is that bloggers produce or come up with the most prescient keywords. Now I like reading and participating in blogs as much as anyone, but that's surely not the only source.
Someone who oversees a dynamic website about your market seems equally valuable. Some organizations are setting up wikis these days, and predictive insights and keywords could be gleaned from them.
Don't forget to listen to smaller voices. Scan and look for obvious changes in external search queries that led visitors to your site. Check how that differs from internal search queries as well. Your visitors will share their new interests and keywords too.