Here's a sweet custom titanium bike we just put together for a guy:

This bike is 21 pounds, that's one pound per inch.  Full Ritchey WCS and Shimano XT, RockShox Sid fork, and Mavic XC717 rims.  Beautiful!

Here's the bike packed in it's case and ready to fly south.  This is a standard size suit case that the airline will accept along with your other baggage.  This one weighs 35lbs packed with tools and other extras.