Network-speed.com is a good site with network analyzing and speed testing tools. DNS lookup , Ping, Traceroute, Bandwidth checker, Firewall port scanner,WHOIS, Browser test and other html tools are available in this site.

It also have an image alt tag/alt attribute creator that can be used to add alt tags to blogs and images.

Tools providing by network-speed.com .

Ping Test
Firewall Scanner
DNS Lookup
Whois Lookup
Browser Scanner
Speed Test/Bandwidth Meter
HTML Tools
Image alt tag/alt attribute creator