Distance sensor from 38kHz receiver
It is possible to build ir distance sensor from 38kHz sensor. You need the sensor and IR led. Sensor's output goes to input pin and IR led's one leg goes to output leg so your controller is able to flicker it.
If the LED pulses at 38kHz (and 1kHz too if just pure 38kHz doesn't work) then the sensor is able to detect LED about 10 meters avay. If you mount them side by side then sensor sees things what are closer than some X range (lets say, 2m) and if there is no things closer then sensor sees nothing. Sounds pretty useless.. But now, lets look at the following graph:
Bingo. So if robot sees something when using 38kHz modulation then robot can increase modulation frequency until it sees nothing. Then it is possible to calculate(look up from table) distance by modulation frequency.
This sounds like something very complicated. But it doesn't have to be. It is possible to use just one modulation frequency. Then it is possible to say if there is an object closer than 20 cm or some other random distance.
And, the width of beam equals led's beam width. More than one sensor can be used but then they should be in shrinktubes or something so random ir light from other sensors couldn't shine at/in them.