One Tail Just Isn't Enough
Although it's difficult for me to look at this piece's title and not think of mutant felines, it doesn't make the statement any less true. If you've ever used the tail command on log files, you'll instantly appreciate multitail. My friend (and LJ reader) Nick Danger introduced me to multitail, and I can't believe how useful it is. multitail will "tail" multiple files, split the screen to display them, notify of log file changes and so on. One of my favorite features is rather than show 100 lines of repeated log, it shows the line only once, and it says, "line repeats 100 times"—simple, but awesome.
Figure 1. Two files at once is just the beginning; multitail is awesome (screenshot from http://www.vanheusden.com).