Gmail is already great, but those Firefox plugins or Chrome extensions makes it even more great.Add your suggestion Subscribe to this list
Makes it possible to schedule emails. And (very useful for sales) let you remind you if you don’t hear back
Gmail's signature is very limited. WiseStamp boosts your signature.
Shows Linkedin-info directly next to your Gmail-conversation.
Total Solution to improving the Gmail Experience. With constant improvements.
Turn your inbox in a massive 'To do'-tool. It'll turn your messages into tasks, tracking and prioritizing, even turning groups of tasks into projects.
Mixmax offers several awesome features: Email tracking, scheduling, templates and organizing meetings. All the features I've seen in other plugins are combined in Mixmax.
Tracks who opens your emails, when how often and from where.
Most cost-effective Email productivity tool for all the professionals.
GMass turns your regular Gmail account into a full email automation app with open / click rate tracking & mail merge.
Yanado is a Task and Project management tool in the form of a Gmail Skin/Overlay.
Free document signing for Gmail attachments.
Streak turns Gmail into a lightweight CRM. Send templated emails, track responses, and more. The "send it later" function on the emails is great if you happen to be working on emails to prospects in the middle of the night. Not that you would be doing that.
FullContact: Contact Management Software & API, keeps all your contacts in one place and automatically up-to-date with the FullContact Address Book.
I've started using this and have been immediately impressed and grateful for the core GMAIL UI improvements and functionality it offers. I can now acccess my contact within GMAIL without navigating out and away. There's more but I'm just getting started.
Sortd Smart Skin for Gmail: Transform your email interface into organized lists and discover a whole new way of working with email.
Super powerful signature management tool with A/B testing and analytics.