Periodically, I get humongous e-mails from people who don't shrink their photos before they send them. Normally, I don't care about this, as I'm never anywhere that a broadband connection isn't nearby. However, there are some people who have mailboxes that can't receive large attachments, typically 10MB or more. So, while researching a solution to this problem, I found ShrinkPic. You download, install, and run this app (it runs in the background -- it automatically puts it in your registry to start when your computer boots).
The direct link to download it is here.