I'd like to suggest that, when you're in the trade center in the 'Manage Your Trades' tab you should be able to select more than one trade to cancel at a time. (Like with messages or subscriptions)
For those who put up food or lions it could make it a lot easier. Going back and forth is time consuming.

I don't know if this as been suggested (I haven't seen it) but if it has please let me know and I will flag for deletion.