I love instrumentation -- compasses, GPSes, watches, chronographs, RFBugs and so on. My OSX desktop always has a CPUMonitor bar showing me the current load, and it looks just swell next to my Network Monitor floating windoid. Network Monitor provides a realtime histogram of bandwidth in and bandwidth out, on your network interface of choice. I use it instead of a mail-chime, since incoming mail generates a signature pattern of bandwidth spikiness that subliminally injects itself into my back-brain, letting me know that there're new messages waiting.