I used FindBigMail to locate the large attachments that I couldn’t pin down easily using Google Search and cleaned a lot of duplicate nonsense and huge files out of my GMail account. This is a very good utility.
The company name Rapportive says it all, build rapport with the people you GMail. I am using the Rapportive Chrome Extension and it pulls up the recent tweets and other information from users you receive and send emails to. This tool is working out well to increase the professionalism of my Customer Relationship Management.