http://www.dailychanges.com shows the volume of domain tasting, and who is doing it. It should be immediately obvious which domain registrars allow it on a huge scale.
Like I mentioned in another thread, searches I did manually just yesterday morning hadn't caused any names to be registered yet. They are all still available as of checking just now. I used Win32Whois to do this checking.
We should come up with some variations and do a lot of manual searches at Whois.sc, at Yahoo, at Network Solutions, and at GoDaddy.
Mix popular terms and maybe stick with a theme, per site you test. So maybe:
Whois.sc
HomeSecurityLinks.com
FloridaDogRentals.com
Yahoo
BlogPuddingSalt.com
WetCashLocker.com
Network Solutions
PPCAnchorPool.com
KosherPorkChops.com
GoDaddy
FacelessMortgage
WineVitamins.com
Just put some words together that may not seem to fit together, and search a few at each spot. Then check back tomorrow evening or the next day and see if you caught any sharks.