Thanks! I've not done anything more complex than "make the LED flash" with my Arduino (basically the default test project), but didn't realize I could use it to produce sounds (though I was vaguely aware that some audio libraries exist for it). This is going on the project list!With some resistors, LEDs, and a speaker, you can flash LEDs and make noise. Arduino outputs will source 20mA so they can power LEDs. With the addition of a transistor, capacitor, and a resistor, you can make sounds with a speaker.
I have a medium term goal of using it to try and operate an old SN76477NF Complex Sound Generator that I bought off Ebay a while back.