(Updated June 2012)
EngineReady Negative Keyword List – Download the world’s largest negative keyword list. A list of 420 negative keywords by major vertical, along with a list of general negative keywords.
Google Top Searches in 2012 – 1 2 trillion searches 146 languages. See what the world searched for.
Mike’s Marketing Tools Daily “Top 500” Keywords – Top 500 searched internet keywords, compiled from a database of over 330 million search terms, which are extracted from popular metacrawlers Metacrawler and Dogpile.
MySeoBlog Highest Paying Niches for AdSense CPC – Although this list was compiled in 2008, it still makes for interesting reading and can provide a starting point for niche ideas.
Soovle Top Keywords for Today – Today’s top internet keywords. This list is compiled from the four major providers of search suggestions and then aggregated.