as for equalisers, about the best indash eq you are going to find is a 7 band graphic equiliser which are as effective as anyone would like them to be. they are more for looks then actual equalisation as most headunits have great eq's on them these days.
if you had the money you could put a screen in the top slot and put the headunit into the bottom slot. Just connect the screen up to a playstation, xbox, dvd player ect and you have games and entertainment in the car. Note: This can be an expensive exercise!
alternatively you could always get a map pocket:D