Here is a free online tool to research the popularity of new or old TLDs, ccTLDs and IDNs.
We took the Alexa top million site list and then created an interface that will allow you make queries and find sites based on the rank, TLDs, strings in the domain name, Non-ASCII characters in domain names (International Domain Names).
You can use it to list all the sites that use a specific TLD (like Guru, Tools, Today, COM, US, UK, etc). You can also easily find which .GURU site ranks best, how many .TODAY sites are in the top million etc.
You can search for domains that have a specific string. For example, type in “ideas” to find all domains that have the word “ideas” in them.