Firewire 800 to USB??
Is there an adapter or some way that I can connect my firewire hard drives to a MacBook Air (2011) with only USB ports?
MacBook Air, Mac OS X (10.7.3), iCloud Inbox
Not USB, but if yours is a mid-2011 or later and equipped with Thunderbolt, then you could use this;
http://store.apple.com/us/product/MD464LL/A/apple-thunderbolt-to-firewire-adapte r?fnode=51