QuickTime 7.6.6 for Leopard is recommended for all QuickTime 7 users and according to Apple brings about "general reliability improvements for iMovie." Additionally, the update addresses a long list of security vulnerabilities related to maliciously crafted audio or movie files that could allow attackers to cause crashes or run arbitrary code. The update is available via Software Update or the Apple Support Downloads page. (Free, 68.63 MB)
Open Links from Mail in the Background
Tired of switching back and forth between Mail and your Web browser every time you click a link in a TidBITS issue or other email message? Here's an easy workaround. Hold down the Command key when you click links in Mail to open them in your browser without switching away from Mail. That way you can keep reading in Mail and then read all the Web pages you've opened.