When in need of help when trying to find domain names, these are the sites to visit. Whether its a Who Is search or info on  domains that have just expired, these resources will help in your quest to build a strong domain portfolio.

Whois.sc
Enter a keyword to see which of its extensions are taken. One of the best tools available when looking to register a new name. Surprisingly, this tool used to be even more effective but they decided for some reason to remove domain suggestions and the ability to just track expired to deleting names.

Deleted Domains
One of the best resources for keeping track of expired and deleted domains. You can either use their Power Search to find expired names that are now classified as a registrar hold or ones that have already been deleted. For more timely info, use their Today’s Deletions feature to find names that just became available. You can even search for registrations of a keyword over a 2 month period.

Drop Market
Dedicated to finding good available domains in various extensions. DM has incorporated the following Zone files into the service, with more to come : com/net/org/us/info/biz/name.

SnapCheck
Find out which expired names have Snaps on them or not just prior to deletion.

Imposed.net
Allows you to search through quality domain names that are available such as ones without hyphens. This services cost $30 for 6 months and about 1000 names are added each day. Definitely a good buy for domainers looking to manually register most of their names.

Deleted.com
Offers drop lists and several domain tools.