BetterZip 2 has a queue for executing multiple archive operations in an ordered way. You can let Mac OS X decide how many operations to run at the same time or set it manually.
The queue will be used automatically when you start an archive operation by using one of the BetterZip services, when doing a direct extraction (holding down ^⌘ while double clicking an archive in the Finder), or when dropping files or archives into the queue window.