I look forward to lot of my Magazines, but two that are really helpful for Electrical Circuits are Electronic Design and Electronics Design, Strategy, News.
Electronic Design has Ideas For Design and Electronics Design, Strategy, News has Design Ideas.
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…