Remember that if a colour is in use can look at the plural or add a simple word like THE in the front.
A great example is TheRed.ca which is a developed site running on that domain.
1. Red.ca - Not in use, Owned by MapleDots, forwards to a for sale page
2. White.ca - In use by Richard White Architects
3. Blue.ca - Not in use, Forwards to N49 Web Design
4. Black.ca - Not in use, forwards to a For Sale lander
5. Green.ca - In use by the Green Party of Canada but forwards to GreenParty.ca
6. Orange.ca - In use by The Orange Benefit Fund but forwards to OrangeBenefitFund.ca
7. Yellow.ca - Kind of in use but forwards to CanPages.ca owned by YellowPages.ca
8. Pink.ca - Not in use, Owned by MapleDots, forwards to a for sale page
9. Purple.ca - In use by the Purple Company but site is suspicious because it never changes
10. Brown.ca - In use by Brown Communications group