Gmail manager is a small Firefox addon which lets you manage your Google mail account and login to multiple gmail address to check mails quite effectively.
As Gmail manager allows multiple email check option,you can also view mail snippets which flashes as a small window showing 30+ odd unread messages without the need of opening Gmail website.You can also switch between your different Gmail accounts with a single click.
The installation of the addon is pretty simple,download Gmail manager and restart the firefox browser.The addon will pop up a window where you can add your Gmail username and passords,alternately you can import/export Gmail login details.A small icon appears in the status bar reflecting number of spam mails and unread messages in your inbox!
Click here download the addon