I hate a solo, mainly because the sort of music most bands I've been part of play doesn't lend itself to such things. Either that or I lack the imagination to come up with anything satisfactory.
Could try a graphic equalizer in the effects loop. There's a Peavey Q1311 31 band that covers pretty much everything on Ebay for £40 at the moment. Guess it could go in the effects loop. Also good for tailoring sound for different situations.