
I'll start with these:
- YouTube video player borks if you change your system time
- Apple Java's applet browser plugin would throw an ArrayOutOfBoundsException to *everything* if it was out of date (interestingly, appletviewer doesn't)
- OpenBSD 5.5 + XFCE *required* a working Internet connection to open a Terminal, otherwise the whole system would hang
- Adobe Shockwave for Director on Mac OS X gets glitchy and sooooo.. slooooow... if it doesn't like your installed Flash player version