I know what you mean. Some sites i have been looking at.
A few sites to whet your appetite:-
MotorBike Related: Go on you know you wanna :P
http://www.horizonsunlimited.com/hubb/ - THE site if yer off on a bike.
http://www.advrider.com/forums/index.php (check the Ride Reports thread)
http://www.ukgser.com/forums/ - An informative site, friendly people
Bike: (without the motor)
http://www.alastairhumphreys.com/ - Now THAT's a ride!
http://en.wikipedia.org/wiki/EuroVelo - European cycling
http://www.tour.tk/index.htm - Man and wife on bike - sold the lot and went!
https://www.adventurecycling.org/index.cfm - American Cycling
http://www.crazyguyonabike.com/ - Looks naff but excellent site.
Organized trips: (if you don't wanna go on yer own and go on a more organized tour)
http://www.oasisoverland.co.uk/
http://www.dragoman.com/
http://eoe.org.uk/
Inspiration:
http://www.travelblog.org/
http://www.travelpod.com/
http://www.lonelyplanet.com/thorntree/index.jspa - THE travel info site
http://www.jupitalia.com/ - The reason why Ewan and Charlie went - Ted Simon.
By Rail:
http://www.seat61.com/index.html - The only one you will need probably.
By Sail:
http://www.nonstopsail.com/
I am looking for "something" myself. My adventure would be - any of the above! There is plenty out there!