It would be really useful if you could save custom search queries using a description. When you build complex queries it is rather cumbersome to build them again each time.
Related to this I have another whish: It would be great to build queries where you can nest different subqueries. something like
"(((artist:x and title:y) or (year:2012 and not genre:rock)) or genre:country)", preferably with using a graphical editor as complex stuff is faster to do when you can just type away (assumed you are knowing the syntax of course)