I often am on the internet when my wife picks up the telephone upstairs
thus breaking my connection to the ISP. Does anyone have a circuit
or know of a source for and "offline" indicators what will flash an LED
or something so the wife will know I am useing the internet downstairs??

http://www.hobbytron.com/CK007.html is one such.

There are 'self-powered' circuits around for this which do not require
a battery, but I'd recommend avoiding them. Any circuit which draws
more than a very small amount of current from the phone line may
either take it off-hook accidentally, or trigger a wiring-fault
indication at the central office.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!