Last night during some planned server maintenance, I pushed through two updates that have been pending for a while:
20 Character Usernames
Previously, usernames were limited to 12 characters. You can now make your username up to 20 characters long. If you’d like to change yours go to http://readitlaterlist.com/pass. While you are there, if you haven’t already, you should add a password reset email so if you ever forget your login you can retrieve it without contacting me 
Tag Editing
Before the update, tags could only be added to items, not removed or edited. This limit is no longer in affect. You can edit and delete tags and the changes will sync as well.