Mac OS X only Freeware applications Wallpaper Clocks and Desktopia set time-specific wallpapers to your desktop, providing you with a fun and effective way to keep an eye on the time with attractive wallpapers (though you could set different wallpapers to remind you to change work modes or tasks).

Install and run Internet Explorer for Windows 5, 6, or 7 on your Mac with free, open source application ies4osx (it's not that hard).