A few of us here are fans of retro-computers (that us, 8-bit machines from the 1970s and 80s) and we're amazed at the following technique described by Chris Osborrn which uses a Raspberry Pi to help get these clasic machines connected to the Internet.
The first hurdle is finding a machine with a serial port that would have connected to a dial-up modem to run and some useful software, for example a telnet client, BBS software etc. The next step is get get an RS232 or matching serial to USB cable, whose type will depend on your original computer.
Once you've completed that part the next is easy - get a Raspberry Pi and the TCPSSER software installed onto it. Chris explains this and then shows how the RPi can emulate a dial-up modem with full AT commands to the old computer.
Then it can simply "dial up" but instead of ATDphonenumber you simply use ATDhostname:port. For more on this method and some other retro-goodness, check out Chris's interesting website. While on this topic, consider the following video with Lon Seidman who demonstrates this process working by running a BBS on an Applie II system:
If you're looking for a more permanent way to mount circuitry to your Raspberry Pi, check out our PiBreak - the prototyping board for the Raspberry Pi. It provides labelled breakout pins for all GPIOs, a large prototyping area with solder pads, and power rails for easy power connection:
Furthermore the PiBreak also includes mounting hardware to firmly attach it to your Raspberry Pi using a nut, bolt, and spacer - and is compatible with all revisions of both model A and B Raspberry Pi computers. For more information about our new PiBreak board, our Getting Started guide, and to order - visit the product page.