LAN Speed Test

Description: LAN Speed Test v4 is a simple but powerful tool for measuring the speed of your Local Area Network (LAN) wired & wireless, file transfers, hard drives, and USB Drives.
Interface: Windows GUI, Mac GUI
License: Free for basic features.
Functions: Test network, file write speed. Has a server (optional) component and a client component.
Homepage
Platforms: Windows x86
Commentary: Similar to iperf, this tool runs speed tests with native Windows binary
Usage Example: Setup server  (if needed) and run client (portable) and test.

Screenshot (client):

Screenshot (server):