NetSurveyor Professional is a new type of diagnostic tool that puts a different spin on WiFi troubleshooting -- emphasizing performance metrics over measurements of RF signal strengths. NetSurveyor-Pro is used to test the performance and reliability of a WiFi network and help identify and troubleshoot problems. Furthermore, NetSurveyor-Pro also allows you to concurrently test multiple (up to five) WiFi connections. NetSurveyor-Pro is a software-only product that uses your 802.11 adapter(s) and access point(s) -- no additional proprietary hardware is required. Novices through experts will find NetSurveyor-Pro most useful when installing, testing, and troubleshooting 802.11 adapters and wireless networks. At a fraction of the cost of more expensive solutions, NetSurveyor-Pro provides a more accurate picture of a WiFi network from a performance perspective.

Ultimately, the bottom line for any network (wired or wireless) comes down to throughput performance -- that is, how many bytes-per-sec can be transferred from one node on the network to another. The dBm and RSSI values that are often referred to in the context of wireless networks don't mean much if you can't somehow relate them to a performance metric. Before we can really begin to troubleshoot a wireless network we need a way to benchmark its performance, so as modifications are made we can determine whether or not they really make a difference in the network's performance. This is where NetSurveyor-Pro comes in. It is a simple tool that allows benchmarking of one or more wireless networks.
Category:   Software > Monitoring/Scanning
Software > other WiFi stuff

kwavecontrol is a kde-monitoring tool for wireless devices showing diverse information like signal quality, bitrate, e.g.
Category:   Software > Monitoring/Scanning

X Net Strength is a small utility for monitoring the wireless signal strength of 802.11b cards under Linux. It is written in C and only requires xlib.
Category:   Software > Monitoring/Scanning

witools is a small collection of utilities to aid in the exploration of 802.11 wireless networks.
Category:   Software > Monitoring/Scanning

KisMAC is an opensource and free stumbler/scanner application for Mac OS X. It has an advantage over MacStumbler/iStumbler/NetStumbler in that it uses monitor mode and passive scanning.
KisMAC supports several third party PCMCIA cards - Orinoco, PrismII, Cisco Aironet, Atheros and PrismGT. USB Prism2 is supported as well, and USB Ralink support is in development. All of the internal AirPort hardware is supported as well.
Please note: This program is not intended for novices, but for professional users. Take this as a warning
Category:   Software > Monitoring/Scanning