Overture with the extension i.e. domainname.com rather than domain name.
You have to watch out though for developed sites around the phrase. These could skew the Overture results. You could think its pure generic type-ins but its not.
Example. Cheap-Sheets.com is a massive developed web site but I dont know it. I am evaluating domain cheapsheets.com. I look at Overture and see skewed results. The more you workwith it the more you will learn i.e. you have to make a few mistakes.
There is an Overture database at
www.digitalpoint.com as Overture itself is working intermittently at the moment.
====
If your looking at a domain name to buy which is parked then there are good stats available. Make sure to ask for these. If you dont get them you have to ask why. If your looking for generic type-ins check the history of the domain on
www.archive.org. Was it a massive developed site with links? Do you want this traffic, can you use it?