Mode Zero

I suppose it counts as a project - I've published the little reverse detector circuit I was working on on the Taycol site:

http://taycol.tk/relay1.html

To pre-address Phil's comments, a PIC or Arduino is not really suitable for this environment. Huge induced spikes play merry hell with modern logic. An Op-Amp seems to work ok with no filtering, but the Taycol would fit better with mercury-arc rectifier technology...

Nothing wrong with old skool Dodgy, its a perfect solution
Back in the day before FETs my NE543 model car speed controller with reverse worked in a similar way,
predominant ESC output operates a relay or not, exactly the same principle

That's what a design ought to look like! The only way it could be bettered would be if it were on the back of a fag packet...