Tracking multiple shipments can be a pain. I usually use a Mac OS X Dashboard widget named Delivery Status. But I also found about an interesting method to track shipments using Twitter!
First of all you need a Twitter account. Follow @trackthis, it will auto follow you immediatly. While you are at it, follow us @sauditech to receive website updates. Then send a direct message to @trackthis in this format:
d trackthis 123456789123 New PC
Where the number is the UPS, Fedex, USPS, DHL, etc tracking number and the text after that is the label for that shipments. Now you will receive direct messages from @trackthis whenever there is a change in the delivery status. You can learn more about trackthis at their website. They also offer tracking using a Facebook application or though an e-mail message.