There's a lot of stuff that could be controled via relays, almost annything that just has to bee turned on or off ( obvusly you can not us a realy as a dimmer ) i want use the relay to unlock the front door as my bluetooth phone gets in range of the reciver ( posibly checking and confiming the MAC address for the phone )
But theres a lot of different hardware :-( so it migth be hard to do a generic driver for this.
Unless someone can use/ incorperate the linux open source drivers used in the MATplc project
http://mat.sourceforge.net/manual/io/parport.html , i'm sad to say that this is outside my knowlege as i 'm not a programmer.
By incorporating this into the PLUTO source lot of hardware is coverd ,even the paralell port part.
Conecting relays to the paralell port is easy all you need is a relay ( obviusly ) resistor ,psu, and a transsitor and some soldering skills
a schematic with optocoplers ( to stop wite expensive smoke coming from your pc ) is found her :
http://www.geocities.com/dsaproject/electronics/relay/relay_board.html