The Rigol DS1052E is the de facto oscilloscope for any tinkerer’s bench. It’s cheap, it’s good enough, and it’s been around for a long time; with the new 1054 zed model out now, you might even be able to pick up a 1052E on the cheap.
[wd5gnr1] came up with a really interesting piece of software that allows a Linux system to control most of the functions on this popular scope. With just a USB cable, you can read and log all the measurement of the scope, save waveforms in CSV format, and send data to gnuplot and qtiplot.
Since the 1052E has been around for such a long time, there’s a bunch of software out there that takes advantage of the nifty USB port on the front of this scope. If you need a cheap spectrum analyzer, here ‘ya go, and tools for the .WFM files native to this scope even exist for Windows. [wd5gnr1] even says his tool can probably be ported to Windows, but ‘just use Linux.’