I have been playing with some Rasberry Pi,
and Beagle board stuff here are some notes:

Rasberry Pi

Old Receiver into Bluetooth Receiver:
This was the first one i did:

You need to create a Balena account, but it will expose you to alot of board programming stuff.
 BlueTooth Receiver 

Transmit FM:
my favorite
This uses the Micphrone project in conjunction
with the FM Transmitter app to broadcast the Microphone
on a FM  frequency ( 100 and 105.7 )

Here is the website with the tutorial I followed:
Fm Transmit

To play a wave
sudo ./fm_transmitter -f 100  -r acoustic_guitar_duet.wav

Here is the command to transmit from USB MIC on FM 105.7
arecord --device hw:1,0 -c1 -d 0 -r 48100 -f S16_LE -V mono | sudo /home/pi/PI_FM/fm_transmitter/fm_transmitter -f 105.7 -

Connect to a Bluetooth device:
Send USB Mic to bluetooth device
Mr Mickrophone

Get Old Printer on Network:
Moved my old HP Deskjet 3845 out of office and out of the way

Used this tutorial and cups
Printer On Pi

I had to use version 3.18.6 OF HPLIP with custom setup and uncheck Qt4 & Qt5 interfaces.

current HPLIP

the hardest part was getting the HP Deskjet 3845 Driver.
( a 3840 cups driver that worked was in 3.18.6 ))
Old Vers of HPLIP

I also had to do this:
lpadmin -p  HP_Deskjet_3840 -o usb-no-reattach-default=true

then a restart of the Pi.


Here is a link to a simple SDL 1 app that will run on a Rasperry Pi.