Malware
The other section of Google Webmaster Tools that people rarely check is Health > Malware. Malware is actually one of the biggest threats online. If you fail to protect your site and someone installs a malicious script on it, Google will ban you from their rankings immediately, and then maybe include you back if you manage to convince them that your site is clean again. The malware section in Google Webmaster Tools will let you know about any issues that might require your action.
That’s it for the 10 things webmasters often forget about doing. Do you want to mention something else that deserves equal attention?