MyLanViewer Network/IP Scanner is a powerful Netbios and LAN/Network IP address scanner that assists in locating IP addresses, MAC addresses, and shared folders of computers on your wired or wireless (Wi-Fi) network.
LizardSystems Wi-Fi Scanner is a free app that locates visible wireless networks along with all corresponding information, including the network name (SSID), signal strength (RSSI) and quality, MAC address (BSSID), channel, maximum and achievable data rate, security, and much more.
ChrisPC DNS Switch Pro provides you with a graphic user interface to select a network adapter/card and change its corresponding DNS with the selected DNS. ChrisPC DNS Switch Free available here.
ChrisPC DNS Switch makes DNS changes more easily and lets you choose the one that fits your browsing habits from a series of alternative DNS. ChrisPC DNS Switch Pro also available.
Farbar Service Scanner, or FSS, is a lightweight, portable tool for diagnosing network connectivity issues directly related to missing or corrupted Windows services.
WifiInfoView will quickly scan all the wireless networks in your area and then provide you with extensive information about them; great for diagnosing a connectivity issue or locating your router's model number, and more.
Complete Internet Repair does exactly what it says. It attempts to repair everything internet-related, including networking problems. Video tutorial and a portable version are also available.
VOVSOFT Network Alarmer allows you to check the availability of network devices using their IP addresses and can send automatic phone calls or email notifications in case of issues.
TCPConnectProblemView is a tool for Windows that monitors the TCP connections on your system and displays an alert when software tries to initiate a TCP connection, and there is no response from the server.