For snow kiting on lakes, you need an ice screw. I found it helpful to carry one with me too. Here's a handy way to store one so it's always with you - PVC tube and bungee strap: (credit to Pete G. in lake City for this idea):
Bar straps to secure lines (if yours doesn't have them). Cut a small strip from a bicycle inner tube:
Line tamers - these are handy for keeping the lines organized if you share the bar between different kites. You can order online at: http://www.kitelobster.com/
What to do with all the wet gear when you are done? Go to Fleet Farm, or an army surplus store and get a few army surplus laundry bags. These nylon bags are lined and waterproof. Stuff your kite, wetsuit, harness, etc into these and your kite mobile stays dry.
Kite pump - use one of these $25 battery operated pumps to get the kite pumped up and then finish it off with the hand pump.
Travel bag. I have an NSI deceiver for when I need to travel with a board and kites. If I'm just taking kites and renting a board, a standard golf bag works pretty well and is a little smaller too.
Mark