I'm not sure if this is something other people would find useful - but there's only one way to find out...
Recently I was working on a project where I needed to have a constant graphical display of a temperature input, at fairly high speed. (It was the rate of change and general waveform I wanted to see, not just the actual temperature, hence the need for a graphical display).
I made up a bargraph display with an ATMega chip and an old monitor I had spare, using horizontal line widths scrolling up the screen, so I could see what was going on whilst testing. It was relatively easy to change the bar colours to indicate different temperature levels and status etc.
This was very useful but what I wanted then was an on screen digital readout as well, which is a lot more difficult than just horizontal lines. I had a think about it and then got a bit carried away. In the end, I worked out how to do a colour display with 70 rows of chars by up to 40 high, but I think 25 lines high would be better, 70 x 25 = 1750 chars max.
An advantage with this is that it could do vertical bars as well as just horizontal, and output all kinds of useful stuff during testing, which would be helpful on top of the normal breakpoint and trace facilities offered by the debugging tools.
The problem is that it isn't really worth the effort to make a display of this sort for just one person to use. I was wondering if other developers may find such a display useful either during testing or as a permanent display for certain types of project. With a single serial pin out of a microcontroller, providing a standard monitor output via the display board, even a modest 8 pin microcontroller could display all kinds of data. It would give a lot more scope than small LCD panels anyway.
A natural question at this point is "well, it depends on the price". I've had a think about it and probably a basic version display board with certain limitations would be from around $10 or €8 (if they were made in quantity), up to $50 (€40) for a top end version with everything.
I'd be interested to hear if anyone thinks this sounds like something useful. If so, I may take it further. I used to work for a digital scope company, so it would be nice to work on a stand-alone storage scope with VGA display if I could get this off the ground first - it would make lots of old monitors happy to be useful again!