Passwordless signup or guest mode would be good - I want to try your app however I do not want to commit yet by creating a nother password. Perhaps link it to ip + username and once logged in have the option to enable any other ip using a password?
Get yourself a password manager (such as 1Password) that will generate a unique password for every site and remember all of your login credentials for you. This has solved the problem for me.
another way you can go about it is just store things locally on a client machine.. although you may need to explain that unless they sign up their notes will not be saved globally.
That's a great idea and would segway nicely into porting this as a google chrome app. Any tips for storing notes locally? Haven't looked into it just yet.
