wlan.sh

# Use this built-in tools
# May need to install watch

watch -n 1 cat /proc/net/wireless

# Or use wavemon (https://github.com/uoaerg/wavemon)
# Install via apt-get install wavemon
# This will be self-updating

sudo wavemon

# Or, much simpler, follow these steps:
# 1. Buy a raspberry pi camera
# 2. connect it
# 3. start your pi
# 4. enable the camera stuff in raspi-config:
sudo raspi-config
# 5. look at the video preview (make sure you connected a screen!)
raspivid -p 0,0,640,480
# 6. point the camera at your wifi-adaptor
# 7. interpret it's led blinking pattern according to the manual

You also could develop a neuronal network that recognizes the state of your wifi adapters' led. So that the last step (7.) will be done by your pi too. Just sayin'