A large percentage of the readers here are stock photographers, more specifically microstock photographers. Keywording images for stock photography, or for any use really, is a daunting task. MicrostockGroup has created a keywording tool that helps photographers brainstorm for keywords they may have missed. Even if you feel you are a pro-keyworder, there is always a word you forget to ad, or a word that another culture uses but is not familiar to your own culture (such as flat or apartment in the UK and American, respectively)
In addition to helping photographers keyword their images, the quick tool can also help image buyers brainstorm for search terms. If a buyer is searching for pancakes, for example, but wants to know popular keywords photographers are using for images with pancakes, the tool provides a nice visual for the most popular words used.
The keyword tool should be pretty self explanatory, but if you need a little how-to video, here it is.
The design of the site is focused on efficiency, making selection of keywords as quick and easy.