flightreference.info loanreference.info s*xreference.info (you know what vowel) hotelreference.info hostreference.info any value? regged at 1 euro each.
Despite not liking the .info suffix, these names are okay. You won't get rich off of them, but if you develop them, they could get traffic. If well executed, they could each make more money than they cost to maintain their registration. A great amount of your effort, of course, will get siphoned to the .com of the same name--so it's just a matter of assessing whether the effort is worth it.