This has to be the most quick-and-dirty data visualizer out there: I wrote an ascii art plotter script that takes a column of numbers on stdin and throws out a plot on your console. I’ve been using it for several months to quickly look at numbers on the commandline, especially from logs and such. (Back in school I would use gnuplot for this; R is good too. But sometimes you want to move really fast, esp if you have a few hideous perl -pe one-liners on your hands and mucking around with temp files will interrupt your flow.)
$ cat time.log | conplot 14601 oooooooo oooooo ooooooooo oooooooooooo 11269 oooooooo oooo ooo oooo oo ooo 7271 ooooo oooo oooo oooo oooo oooo 3272 oo o o oo ooo ooo -726 0 76826
I must say, it’s way easier to throw up some code on GitHub than on to SourceForge, which is the only other open source code hosting service I’ve used. I guess Google Code is their biggest competitor in that respect; I haven’t tried it.