WIRESHARK and KISMET

Improving by 2 points to reach the number 5th spot is wireshark. The 5th spot is combined spot for kismet as well as wireshark.
 It is the most preferred wireless security assessment tool and a single of its type in this field. It is a must have tool for all wireless junkies. Wireshark is a GTK+-based network protocol analyzer, or sniffer, that lets you capture and interactively browse the contents of network frames.  


Kismet is an 802.11 wireless network detector, sniffer, and intrusion detection system.  Kismet will work with any wireless card which supports raw monitoring mode, and can sniff 802.11b, 802.11a, 802.11g, and 802.11n traffic (devices and drivers permitting                                   DOWNLOAD