GCount - An application for Mac OSX that alerts you to new mail.
gDisk - An app for Mac OSX giving the ability to turn Gmail accounts into storage drives.
gFeeder - A small ticker for your Gmail that will let you know at a glance what's coming in for you.
GetMail - Allows you to migrate your emails from Hotmail to your Gmail account.
Gmail Drive - Another tool for turning your Gmail account in to a virtual storage drive, this one works directly from inside Windows Explorer.
Gmail Loader - For Windows or Linux, aids you in loading your email to your Gmail account.
GMailFS - Turns your Gmail space into a virtual drive that your Windows Explorer can see.
GotMailG - A Mac widget to display the number of unread messages in your inbox.
POP3/IMAP server for GMAIL in JAVA - Allows you POP3 access via your favorite mail reader to your Gmail account, IMAP still in development.
Send To GMail - With one click, you can back up any file you want from your computer to your Gmail account.
Better Gmail - Combines some of the most popular Greasemonkey scripts in to one extension. Includes things such as skins, saved searches, keyboard macros, and more.
Delegate to Remember The Milk - Adds a button to Gmail and allows you make to-do lists.
Dragdropupload - Allows you to drag your files to the attachment box.
GCalQuickTab - Allows you to quickly change between Google Mail and Calendar with keyboard shortcuts.
Gmail Checker - Allows you to check your Gmail for new messages.
Gmail Manager - Allows you to not only manage multiple accounts, but know how much mail and spam they have.
Gmail Notifier - Get notifications of new emails right in your browser.
Gmail RTL - Adds direction buttons to your email.
Gmail S/Mime - Allows you to send and receive encrypted emails.
Gmail Skins - Change the look of your inbox, insert HTML tables, use emoticons and more.
Google Toolbar - Official Google release of a toolbar with Gmail features.
Gspace - Turns your Gmail account in to a virtual web drive that you can upload files to and store them.
gTalk Sidebar - Incorporates Google Talk into your sidebar.
GTDInBox - A Getting Things Done tool that integrates into Gmail, helps you get organized.
WebMail Notifier - Checks your Gmail account for unread emails; works with other email services also.
Clean Gmail Print - Removes the Gmail logo when you go to print out your email
Folders4Gmail - If you prefer the old style of sorting mail in folders over labels, this is the script for you.
Force HTTPS for GMail, GCal, and GDocs - Forces the corner links in the Google apps to change over to HTTPS.
gDate2Cal 0.1 - Turns dates in Gmail in to links to take you to that day in Google Calendar.
Gmail + Reader Integration - Lets you use Google Reader with your Gmail account.
GMail Attachment Icons - Shows you an icon that lets you know what type of file is attached to an email without opening it.
Gmail attachment reminder v2.4.1 - Reminds you to attach a file your email if it appears you haven't.
Gmail Contact List - Adds a contact list near the â€œToâ€ field in compose.
Gmail Conversation Preview - Right click on a conversation to get a preview of it in a bubble.
Gmail Date Search - adds a Search by Date button to Gmail's search form
Gmail Delete Button - RED Color - Turns the delete button red so there is less chance of hitting it accidentally.
Gmail Emoticons! - Puts an emoticons button next to the â€œCheck Spellingâ€ button to allow you to enter numerous different smilies.
Gmail Encrypt - Allows you to encrypt outgoing emails and create encryption keys.
Gmail FavIcon Alerts - Turns the Gmail favicon in the address bar in to a new mail alert.
Gmail from address selector - Lets you change the reply-to email address depending on who you are sending to. (i.e. sending to someone like â€œ@work.comâ€, you choose your work address as the from address)
Gmail Full Width - Removes the advertising block on the right so that your mails take up the full width.
Gmail Google Calendar sidebar - Adds your Google Calendar to your Gmail display.
Gmail Lite - Removes ads, the footer, stars, and chats.
Gmail Macros - Allows you to create more keyboard shortcuts to speed up your Gmail experience.
Gmail Multi-User Login - For those of you with more than one Gmail account, this will give you a drop down menu with all of your accounts listed.
Gmail Multiple Signatures, plus Float - Will change your signature based on what return address you enter.
Gmail - One Click Conversations - Allows you quick access to the most recent conversations with a contact via a one click button.
GMail Header, Navigation and Ads Switcher - Can choose to hide or show the header, navigation bar, and ads by clicking a button.
Gmail - Zip Attachments and Download - Allows you to download all the attachments of an email by merely clicking on the paper clip icon.
GmailTo -Opens mailto: commands from websites in Gmail compose.
Google Air Skin - Script to use Air Skin in Gmail, Google Calendar, on Google.com, and Google Reader.
Label Colors - Lets you choose the colors of various labels so you can tell them apart easier.
Plaxo4Gmail - Allows you to sync your Gmail with your Plaxo info.
Saved Searches - Allows you to save a Gmail search so that you can just click on the saved search to do it again.
GBooks - Allows you to turn a Gmail account in to a bookmarks server.
gExodus - Allows you to export your emails from another account to your Gmail account in mbox format.
Gmail icon generator - Allows you to create a small graphic of your Gmail address to place on websites so that you may display your address without spam bots reading it.
Gmail Music - Store MP3 files in your Gmail account and play them on any computer.
Gmail Todo - Turn your Gmail into a helpful â€œTo Doâ€ list.
PhpGmailDrive - Retrieves a list of attachments from a Gmail account and enables you to list them on a website or blog for others to download.
You've Got Gmail - A plugin for the Trillian messenger program that lets you manage your accounts. (via)