Windows GUI, lets you query adn browse mibs - a great Windows tool.
Here is a great site, they sell pro versions of SNMP
Search for and download Mibs
Graphically view and download mibs, this link is for the F5 BigIP
Usage notes, I found that Windows XP and cygwin Net-SNMP utilities share Windows enviroment variables which detail where mibs are stored. I found this when working with a specific SNMP tool and not seeing all mibs being processed, to get both tools to use the mibs I changed the Windows enviroment values.