Like most enlightened individuals, I've got a MacBook Pro that I need to tote from location to location.  Any suggestions on a tank bag that will support the girth of a MBP, with supporting power cables, mouse, and ideally a pair of shoes? 

I've been using a backpack, but I can get better mileage with a tank bag. 

Thanks!

I dont have a tankbag but a tailbag is my personal commuting bag of choice.  I have a cortech sport tailbag and used it on my 695 and now i use it on my 1098.  It fits a big bulky gateway laptop with power cords and a mouse along my lunch and a pair of jeans or shorts.
http://www.newenoughhp.com/luggage/tail_bags/cortech_by_tour_master/sport_motorcycle_tail_bag.html

If your using it on the 695 the bungee cords it comes with will work fine.

If for your 848 u can get a tie down strap that use for say a canoe and thread it through where the bungee cords would go in the bag then form an X on the bottom of the bag.  The passenger seat will slide right in and keep it secure i can post pics later on if you are not sure how to do this.

If you can't use a tailbag sorry i am no help 

Thanks for the info.  I'll have to check one out to see if it'll hold a MacBook Pro.