ABC Tires:
For my ABC Tires example they offered a ton of modifier words and about a dozen search terms (including the modifiers I was able to make many additional keywords). A couple of the terms they showed me were obvious random one off type searches that a random surfer searched for twice, but many of the terms lead to conversions. The lateral search and thesaurus make WordTracker great.
Digital Point Keyword Research Tool:
try Digital Point's Free Keyword Research Tool free
Digital Point's keyword tool compares Overture and WordTracker data side by side.
Benefits:

• It is quick, free, & easy to use.
• It gives multiple suggestions side by side.
• It is the sum of the pieces of WordTracker and Overture's Search Term Suggestion Tool.

Negatives:

• It lacks some of WordTrackers more advanced features.

Keyword Intelligence:
subscribe to Keyword Intelligence ($89 to $189 per geographic market)
Benefits:

• It costs ($89 to $189 per market), so not everyone has access to the data.
• Offers 3 months historical data.
• They claim to track 25 million actual web users. Most marketers do not have direct access to spamming this data.
• Shows keyword research data by geographic market.
• Tracks actual traffic.
• Tracks keyword success rates, which shows what percent of clicks ended up in people clicking a result.
• Breaks results down by market.
• They made the industry data a downloadable spreadsheet & the industry data keywords allow you to click on them to pull up the deeper terms containing that search term.
• Viewing the success rates for a good number of terms gives you access to how people search and helps you better understand the psychology of search.

Negatives:

• Considering that Google.com has hundreds of millions of searches daily, the market data from only 25 million web users is a bit limited.
• It has a monthly cost of $89 to $189 per market.
• It offers industry specific keyword terms, but in most cases I found many of the terms overtly generic, and they need to offer additional filtering options from within those industries to make the data more useful. Plus they only list 100 terms per page, which makes some of data not as easy to work with.
• Some of the industry terms are mistargeted. Foo Fighters is not a web development term.
• I did not notice a related terms function. Surely with the data they have access to and some of the company they have partnerships with they could help recommend related terms, and not just terms having the exact words you enter in them. If you are just giving me terms that are extensions of what I am typing in then why don't I just grab more terms by running a Google AdWords account and tracking the keyword data in referal strings?