I give you the humble burrito wrap; it's the seatbag's deadbeat half brother,the bastard offspring of a kitchen towel and a toe strap.
One day I wanted to carry all my stuff (including an adjustable wrench, leatherman, pump, and patch kit) without putting anything on my back, this trick was the ticket.
Thanks again to Grant Petersen's Rivendell bikes for this tip, you can buy a nice piece of cloth made expressly for this purpose from them here
I started with a scavenged square of nice linen from the garage:
I arranged my necessities into a neat semi-cylindrical shape:
now strap that spicy roll up under your seat (especially the gaping cavity beneath a fine leather saddle) and ride!