Our command-line blink1-tool for blink(1) is available now as pre-compiled binaries for Arduino Yun and OpenWrt "brcm47xx" and "ar71xx" devices. (The Yun is a "ar71xx" device running "linino"-flavored OpenWrt, routers like the Asus RT-N16 & Asus RT-N66U are "brcm47xx"-based)
If you're handy with shell scripts, you can whip up a quick bandwidth monitor light alert with blink(1) in a few minutes. blink1-tool is pretty easy, for instance, this causes the blink(1) to flash cyan five times:
blink1-tool --rgb #99ddff --blink 3
Find the pre-built binaries on our blink(1) releases page.
(and if you're interested in how to build OpenWrt binaries from simple Makefiles, check out the Makefile for blink1-tool and the "wrt" and "yun" targets)