Internet Explorer for Mac
I think Microsoft should make a port of Internet Explorer for Mac. I don't personally have a Mac, but I know a lot of web developers who work on a Mac (and actually zero web developers that work on a Windows PC, now that I think of it). I think if IE was available for Mac those developers would do a better job testing their sites with IE and we'd all get better compatibility when using IE on Windows. I run into a lot of sites whose interactive features just don't work quite right on IE (mostly commenting systems) but they all work great on Safari and Firefox. Maybe regular testing on IE is just too inconvenient for all these developers on Macs?