The next most searchable web content on the net is MP3 Music which is getting very big.
You could try doing an MP3 links site or something. Takes a while to build up any income from it and the only way you're gonna make any money is to get click through sponsorships from MP3 portals like MP3.COM, People Sound and music stores like Tower Records and Amazon.co.uk
Check out my site for a bit of inspiration.
I also make money from promoting MP3 artists and bands too.
MP3 Unsigned Artists.com
But like they all say, sex sells!