This tool is designed to simplify keyword research and adwords campaign planning however it also works well for research into keywords and phrases.
Register to use the service then start adding you terms and it will come up with lots of related suggestions.
The best part of this service is that it also gives a good indication of volume - how many times a month a particular term is used. (Refine the tool to show usage within your geographic sales area)
Spend you time on content that already has a viable and interested audience.