In today's busy world, it's not fun to entangle ourselves with multiple email accounts or keep looking/refreshing the mailbox for new emails, but we have to do both at some point of time.
Spiffy is a small utility which gives notifications of e-mails in your Gmail. It's small and simple, if you have ever used Gmail Notifier, then you know the basics. However, Spiffy outdoes Google's original tool with lots of configurable options and with support for multiple accounts, most importantly you can use Google Apps accounts with it. It can monitor up to 5 Gmail accounts (including all the labels) at a time. The auto-refresh time-interval can be custom-set. It will give you a sound alert if you opt for it, and the alert-timing is also adjustable as well as the sound it plays.
Other customization options include making it run at start-up and stay put in the system tray or using proxy servers to connect to Internet. Spiffy can open any installed browser to open Gmail, when the notifications are clicked. Since it saves its settings in a small file, it can even be used on multiple computers or from a flash drive. The portable version of spiffy does not require any installation and is only a single executable program.
Spiffy 0.5.7 is about 275KB in size and is only supported in Windows XP/2003/Vista/7. It requires .NET Framework 2.0; so in case you don't have .NET Framework installed, do install it before using Spiffy. Spiffy has localized versions (not for the portable version) in more than 20 languages and you can opt to download the installable version or the portable version depending your usage.