Whether you want to keep your kit dry or just compress your gear for better packability these compression bags and stuff sacks should be just what you're looking for. You'll find great solutions to help you protect your kit with products from great brands such as Exped, Equinox and Outdoor Research.
Outdoor Research 10L Lightweight Stuff Sack 37646
Outdoor Research Durable Stuff Sack--10 L 37691
Outdoor Research Durable Stuff Sack--20 Liters 37693