Looking for a very good photoreflector? The OPB730F is an EXCELLENT unit!
Left, Middle, Right short range sensors in a small package.
Finally, a drop-in replacement for the venerable, but obsolete, PNA4602! This unit detect standard 38Khz pulsed signals and the carrier frequency. It makes a cheap analog 38kHz signal strength/data detector for robots, secret triggers, and other electronic projects.