The Raspberry Pi Zero is a great partner for the OLPC XO-1 or XO-1.5 laptop.
The XO can act as display and keyboard and share its wifi with the Pi Zero, which does not have wifi. This brings a modern browser to XO users (Chromium).
USB ports are connected with a Standard USB cable (not OTG cable) configured as ethernet , which also powers the Pi Zero.
SSH / X Windows of each OS provides the communication.
The Pi Zero requires adding two drivers (modules-load=dwc2 ,g_ether) to cmdline.txt and dtoverlay=dwc2 to config.txt (Raspbian
Wired connection is created on the XO (using XO's Gnome desktop) and IPv4 tab set to "share with other computers". The connection MUST be created with the Pi Zero DISCONNECTED from XO; otherwise MAC address gets randomly assigned on each boot, which is the source of problems on many posts about Pi sharing of wifi on other computers. Use of SimpleHTTPServer in Python, included in both OS's, provides easy file sharing over the same connection.
Details: http://lists.laptop.org/pipermail/devel ... 39032.html
Pi Zero + 16GB microSD+USB cable < $25 .
A "Sugar Activity" on the XO provides simple access to the Raspbian Desktop on the Pi Zero and is available (free) from the OLPC laptop community.