There are really quite some options all of which depend on what interfaces your "other hardware" and which of these your computer has.
USB:
Host requirement: USB host adapter
HW requirement: USB adapter
CAN:
Host requirement: PC CAN adapter
HW requirement: CAN enabled
WiFi, LAN:
Host requirement: LAN (Connected to a WiFi Access point) or WiFi
HW requirement: LAN or WiFi adapter
I2C Bus:
Host requirement: USB to I
2C host adapter (see here e.g.:
http://www.i2cchip.com/pdfs/i2c2pc.pdf[
^])
HW requirement: I
2C interface
I didn't mention the serial port as OriginalGriff already pointed that one out.
Hope that gives you some ideas.
Best regards,
Manfred