I purchased an Apple IIe Platinum last year and got some pretty sweet programs and games working via ADTPro.
Recently I purchased a Raspberry Pi and picked up a USB-TTL converter while I was at it.
At home I had a DB9 serial to TTL converter, as well as a DB25 to DB9 cable and a gender changer from previous projects.
Finally, hooked up a USB keyboard to the Raspberry Pi and enabled the serial port terminal by adding the line:
T0:23:respawn:/sbin/getty -L ttyUSB0 19200 vt220
to /etc/inittab and restart.Then boot up the IIe with MODEM.MGR and start a new VT220 session using my super serial card at 19200 baud.
Resuling in a very cool serial terminal.