For the past couple of years, it's been possible to use domain names in the .CA TLD that have accented characters.
For example, I'm working on a site called SeniorsVoice.ca / VoixdesAînés.ca.
To register this domain, the client purchased voixdesaines.ca. Once it's registered, any accented variants of those letters can only be purchased by the owner of the basic spelling.
There is some cost to this - the owner also has to pay the registrar for voixdesaînés.ca.