Silicon Labs' EM260 ZigBee/802.15.4 Network Processor
The EM260 integrates a 2.4GHz, IEEE 802.15.4-compliant transceiver with a 16-bit network processor (XAP2b core) to run EmberZNet, the Ember ZigBee-compliant network stack. The EM260 exposes access to the EmberZNet API across a standard SPI module, allowing application development on a Host processor. This means that the EM260 can be viewed as a ZigBee peripheral connected over a SPI. The XAP2b microprocessor is a power-optimized core integrated in the EM260. It contains integrated Flash and RAM memory along with an optimized peripheral set to enhance the operation of the network stack.

Texas Instruments' CC2530ZNP Mini Kit 
The CC2530ZNP Mini Kit ZigBee Network Processor development kit is designed to give a simple introduction to ZigBee wireless networks. The hardware consists of a CC2530 ZigBee device preprogrammed with ZigBee software and an MSP430F2274 microcontroller that controls the ZigBee device.

Jennic's JN5139-xxx-Myy Family
Jennic's JN5139-xxx-Myy family is a range of surface mount RF modules that enables users to implement IEEE802.15.4 or ZigBee compliant systems with minimum time to market and at the lowest cost.

Atmel's AT86RF230
Atmel's AT86RF230 is a low-power 2.4GHz radio transceiver especially designed for ZigBee/IEEE 802.15.4 applications. The AT86RF230 is a true SPI-to-antenna solution.

Silicon Labs Offers Several Different IEEE 802.15.4/ZigBee Solutions
The EM250 is a single-chip solution that integrates a 2.4GHz, IEEE 802.15.4-compliant transceiver with a 16-bit XAP2b microprocessor. It contains integrated Flash and RAM memory and peripherals.