I have multiple times posted on non-standard keyword research tools and services (apart from regular keyword suggestions tools):

• Where to start your keyword research (reviewing online dictionaries and glossaries);
• Tools for keyword brainstorming (on term clustering and related words);
• Using social media for keyword research (on trend comparison and social media tags);
• Organizing keyword modifiers to create long tail strategy (on working with keyword lists);
• How to keep track of popular trends.

And here is another new valuable online tool to help you with keyword research: Tagatum that claims to gather semantic associations from the blogosphere, i.e. to search for any term associations by analyzing its related blog tags (more…)