Linux (and Windows) electronics experimenters

[markw at mohawksoft.com]

I am thinking about making a hardware/software product that will allow you,
the end user, to connect and control projects from your computer.

With the popularity of USB printers, I am thinking that the old tried and
true parallel port is a prime candidate for use.

I want to make a small dongle sort of device that you plug into your
computer's parallel port, it will have a number of digital input and output
ports. I have a couple ideas about the programming API and software support
set.

This is not aimed at the high speed or overly complex data aquisition
market. It is aimed at the home computer hobbiest, people building robots
or car computers and such.

Basically, if you saw this thing in an add in the back of some Linux rag, or
popular electronics, or something, what would you like to see for features?

Linux and Windows support?
Easy - novice - interface?
Advanced expert interface?
Price range?
Expandability?
Build at home kit form?
Web based community support?