Here is a application of an IR Sensor design from Electronic Design:
Use Inexpensive Components To Create An Infrared Close-Object Alert Circuit.
Here are a couple RS-232 projects from Electronics Design, Strategy, News:
RS-232-to-TTL converter tests UARTs with a PC and Hot-swap circuit allows two computers to monitor an RS-232 channel (A PDF version of these Designs is here)
You might want to look through these sites once a month or so to see if there is something that can be applied to your robots… You might even want to submit a design of your own, they do pay a few dollars ($$$) for the designs that are published…