I'm after a beeper/beacon type circuit - where a tone of x Hz is emitted, for y sec, every z sec. I know I can do it with a trio of 555's, but I get the feeling there will be a more elegant way. I haven't really explored programmable ICs, and don't really have the time to learn at this stage....
Any ideas/approaches??

My thought was one 555 running astable (at freq z), which would trigger a 2nd 555 in monostable mode (duration y), which runs the tone gen (555 astable at freq x)...

 

it can be done with two 555, or one 556, or one Cd4093.

 

What if I want a 0.5s beep every 20s? Can I get a 555 down to this duty-cycle?

 

yes a 555 will do that.

 

What you are looking for is an interval timer. Velleman makes a MK111 which can be found on various places using google for less than $10.00.

Or you can build your own for the learning experience.