I always wanted to investigate the feasibility of removing that terrible ugly centre speaker in the dash and getting gauge(s) custom built into the space.
It's not high up on my list though and I don't know what size space you have to play with without the speaker there so I don't know how clean and low profile you could get it.
It would be no good for large gauges though.
In the end it could be a terrible idea. Or it could be awesome.