After trying everything listed in these forums as a fix (both this thread and others), this finally helped (disable IP flood detection within the router).
A history of my issues. Have a late 2008 iMac and late 2011 Mac Mini, both running the latest version of Lion. Immediately after upgrading to Lion (and immediately after purchasing Mac Mini with Lion pre-installed) started experiencing Internet issues. The connection would simply act as if it dropped. It would last a different amount of time every time it happened. It is not my router as all other devices (iPhones, Blackberries & Windows 7 Machines) could access Internet during these so-called Internet issues on machines running Lion.
I like the theory that Lion overloads the router as the connection issues happened most often when Safari would sit on pages that auto refresh (Facebook, Twitter, etc.), or running apps that constantly pinged those services (Facetab, or the Twitter app).
It's still early, as all fixes appeared to work temporarily, however this one seems to boost my connection speed back to where it was pre-Lion. Thanks for the tip!
Although, I'm not thrilled about reducing Internet security. Apple, please fix.