The iPod shuffle being smaller is an exercise in choice. I use my shuffle all the time when I exercise and work around the house so the collection on it tends to be really cohesive or extremely diverse here's whats on it at the moment.
REM - Accelerate
The Hold Steady - Boys and Girls in America
Radiohead - Pablo Honey
Tom Petty and the Heartbreakers - Greatest Hits
The Daysleepers - Drowned in the Sea of Sound
U2 - Unforgettable Fire
Frightened Rabbit - Midnight Organ Fight
The Rolling Stones - Some Girls
Coldplay - Viva la Vida single
What does this collection say - who knows. Most of the uptempo stuff is a reaction to loads of folk-core, slow, quiet, acoustic records that have been filling up the record store and my cabinet. The Dodos, Owen, Bon Iver, Iron and Wine, Kings of Convenience, Junetile and endless amounts of beautiful acoustic quietude thats beginning to all blend and be the same record. I love all the aforementioned acoustic stuff but its summertime, even on my iPod.