Years ago (like, in the OLDEN DAYS, c. 1988-89) there was a fabulous
computer called the NeXT machine.  It came with a nice package of
Objective-C classes and libs called the MusicKit (I think you can get
a contemporary version of it at
musickit.sourceforge.net).
The MusicKit compiled to code that executed directly on a Motorola
56001 DSP chip included in the computer.  Thus it was possible
to run sound-producing processes on the machine with virtually no
load on the host processor.  Back in the days of 25 Mhz 68030
main CPUs, this was a Big Deal.
In order to learn the MusicKit, I wrote a simple app called "Looching"
that generated long, droney tones -- I love to have this gunk going
in the background while hacking, reading, writing, etc.  I guess I was
a Gregorian-chanting monk in a former life.  Something rather remarkable
happened after posting the code to various ftp sites.  I started getting
e-mail from all over zee vorld from people who enjoyed "Looching".
Amazing!  I didn't dub a single cassette!  The Future is Now!  This was
a few years before things like Mosaic (remember that?), the World-Wide
Web, Netscape, "surfing the web", etc. became the independent memes
that have infested our collective consciousness today, and
I was totally enthralled by the possibilities of a networked world.
Since that time, I've become older, more jaded, more cynical, yeah...
all that... been there, done it, been back, got bored... but I still
have a soft spot in me heart for them droney sounds.
By the way, "Looching" was reinstantiated in a number of different forms.
Here's a listing of a few:
Looching2.0.tar.gz
        -- the original source files for the NeXT version
Contemporary MusicKit Looching
        -- a version ported to the new 
        MusicKit
        (maintained by Leigh Smith)
 
jlooch
        -- a version done using
	JSyn,
	a java-based digital sound synthesis/sig-processing
	language.  It can run right in your web browser.
	Most of the time.  Although I did jloochabout the same
	time as mlooch, jlooch makes different
	droney sounds.  Go ahead -- try it out!  The web
	page is fairly similar to this one.
 
mlooch
			-- a version created using
	Max/MSP.
	Ditto the jlooch/mlooch discussion above.
 	Different droney sounds indeed.
crudeLooch.c
        -- a really stripped-down and basic version (no interface)
        in C for RTcmix
 
RTcmix Looching
        -- a nicely-interfaced version done by Luke Dubois using
RTcmix
loochlisp
        -- a version of looching in the lisp language gcl, using
        RTcmix
dlooch
        -- an OS X dashboard widget that makes them sounds
iLooch
        -- an iOS app in the App Store, woo-hoo!
And there are a few named after Nissa the Kitty, too:
mnissa
	-- a
	Max/MSP
	app, with some fun graphics (the *nissa's generally have
	graphical action).
jnissa
	-- a
	JSyn
	nissa, also with some fun graphics.