This is one of those questions that comes up with monotonous regularity, but has always seemed infeasible.

But now it seems that Cypress has a USB Host controller that will work with an 8051:

"The SL811HS is a dual-role capable, i.e., host or peripheral, embedded USB controller. As such, it is designed to be easily connected to a variety of external embedded processors ranging from an 8051 to a StrongARM as a memory mapped peripheral."

http://www.cypress.com/design/re...2381973C6A

http://www.cypress.com/support/a...0F3AEB2978

http://www.cypress.com/support/a...0F3AEB2978

This is outlined in an article in the current Embedded Systems Europe magazine:

"This article has demonstrated the implementation of an embedded USB host using only one additional IC and no third-party software. Cypress’ embedded USB host can support HID devices and hubs with no additional coding ... The present code size is approximately 10 kbytes. All that needs to be done is add the application-specific code for a full system."

http://i.cmpnet.com/embedded/...b04p35.pdf

(yes, it's written by "a senior applications engineer at Cypress!")