Bee-Bot: Bee-Bot is a good physical robot that K-2 students can control. Can connect to a related iPad app or web software/Kinderlogo. Software and curriculum for purchase. Suitable for grades K-6.
Hummingbird Robotics: Hummingbird is designed to enable engineering and robotics activates that involve the making of robots, kinetic sculputres, and animatronics built out of a combination of kit parts and crafting materials. Suitable for ages 10+.
Lego NXT Robotics: a visual programming language used to build LEGO robots. Free curriculum for grades 6-8 that relates programming to STEM subjects. Suitable for grades 3-8+
Play-i: Introducing delightful robots that fuse play with programming for kids of all ages. Will be shipping summer of 2014. See website for pricing. Suitable for grades K-2
Physical Computing
Arduino: Arduino can sense the environment by receiving input from a variety of sensors and can affect its surroundings by controlling lights, motors, and other actuators. The microcontroller on the board is programmed using the Arduino programming language(based on Wiring) and the Arduino development environment (based on Processing). Arduino projects can be stand-alone or they can communicate with software running on a computer (e.g. Flash, Processing, MaxMSP).
Kinect2Scratch: Program the Microsoft Kinect with Scratch. Kinect2Scratch allows data from the Microsoft Kinect controller be sent to Scratch. This means that anyone can write programs with motion control, use gestures, make kinetic games. All you need is a Kinect with its own power supply. Free. Suitable for grades 4-8+
MakeyMakey: MakeyMakey provides learners with the opportunity to control the keyboard by completing circuits. Anything that is a conductor of electricity can be used by clipping the alligator clips and completing the circuit. Great for use with Scratch, creating game controllers, etc. Suitable for grades 3-8+ $
PicoBoards: Using the Scratch programming language you can easily create simple interactive programs based on the input from sensors. Designed for educators and beginners, the PicoBoards is a good way to get into the very basics of programming and reading sensors. Suitable for grades 3-8+. $
Raspberry Pi: is a credit-card sized computer that plugs into your TV and a keyboard. It's a capable little PC which can be used for many of the things that your desktop PC does, like spreadsheets, word-processing and games. It also plays high-definition video. From the website- "We want to see it being used by kids all over the world to learn programming"