If you have five free minutes, you have to check out this post about the $5 cell phone oscilloscope.  The display (including non-existent divisions!) is from an old Nokia phone and the CPU is a PicAxe 08M.

It is things like this that make me want to go back and get my EE degree.  (Not that I don’t like my B.A. in Journalism – but EE is just a little more nerdy)

From the page:

Vertical fixed at 5V full screen (or 0.5V per division, if it had divisions.)

Horizontal Sweep fixed at (approximately) 43mS full screen when over-clocked at 8MHz (or 4.3mS per imaginary division.)

Trigger fixed at 1/2 the peak-to-peak signal (with a time-out when there is no signal.)

Non-portable (unless you want to carry my entire workbench some place.)

Very Affordable (about $4.50; $3.50 for the PicAxe, $1.00 for the phone, everything else I had on hand.)

Visible in Day Light (the LCD Backlight is not connected.)

All Solid-State (using ultra-reliable E-Z Clip Technology.

Source:

http://www.geocities.com/Minimalist_Oscilloscope_08M_Proj/Minimalist_Oscilloscope_08M_Project.html