16-bit bidirectional I/O port
5.5V tolerant
25 mA sink
400 mA total current out
Low standby current as low as 1 µA

https://www.modmypi.com/raspberry-pi/iousbanalogue-expansion-1028/gpio-expansion-boards-1029/modmypi-mcp23017-hat-32-channel-io-expansion-hat uses similar chips in a DIP package.
High-speed I²C ™ interface up to 3.4 MHz

See also the MCP23[S]17 http://ww1.microchip.com/downloads/en/DeviceDoc/20001952C.pdf which is used in the PiDP-10

Lixie is an edge-lit acrylic display for any numeric information you can think of! Clocks, temperature displays, hit counters, and more. Always being a fan of the beautiful typography of a Nixie Tube, the Lixie is a modern spin!

The TAPR TICC is a two-channel timestamping counter with better than 60 picosecond resolution and less than 100 picosecond typical jitter. It has an Allan Deviation noise floor below 1x10-10 for a one second measurement.

Information about magnetic loop antennas, amplifiers and more.

Battery powered, single channel digital oscilloscope which sends its plots via bluetooth to an iOS (Android will be supported later) device for display.

   Analog Bandwidth: 20 MHz
   Sample Rate: 100M samples/second
   Sample Resolution: 8 bits
   Connectivity: Bluetooth 4.0 with 100-ft+ range
   Input Range: +/-40V
   DC Accuracy: +/- 3%
   Offset Range: +/- 40V
   Sample Memory Depth: 4k
   Input Impedance: 1MΩ || 17pF
   Input Coupling: AC/DC
   Resolution: 100 mV/division to 10 V/division
   Compatibility: IOS (Android and Windows coming soon), open source app and protocol
   All day battery life: 8+ hours depending on settings
   Dimensions: 20 mm x 30 mm x 118 mm
   Weight: 56 g

Has Galileo-capable receiver using uBlox {LEA,MAX,NEO}-M8[S] modules.

GNSS receiver based on ublox MAX-M8Q for the Raspberry π. Other interesting parts such as antennas, filtered pre-amplifiers etc. are available too.

Leap second observations, long wave receivers for NTP.