So here are my impressions/some suggestions:
- I don't mind registering an account myself, but I want my team to be able to contribute without creating an account. A "magic" sharing URL would be great (or maybe Google auth, since that's what we use on trello). We like trello because we can have almost everything in one tool.
- It would be helpful if the tool could check if the twitter account, facebook page and G+ page are also available.
- Since we are in the EU we like checking a bunch of other endings as well (.de, .at, .co.uk,...). I see your tool checks those as well, but it would save time if I can enter one name and it checks all my specified tlds.
- there's a bug somewhere that makes the whole list disappear for a couple of seconds and the re-appear again.