When visiting a a web site produces a 404 or another message, check if it's that site that isn't working (down for everyone) or if it's your Internet service provider (just you).

Internet ratings service with visitor profiles for millions of websites and services.

The largest human-edited directory in the world. Also known as DMOZ.

Find out about a domain, including who owns it and their contact information, what server software it runs, usage ranking among many other useful information bits

Get detailed information about an Internet host. Enter an IP address (64.233.167.99), domain name (google.com), hostname (py-in-f99.google.com), or AS-number (AS15169) to get detailed dns information including reverse dns and forwards, whois information, who hosts the machine, and if it's listed in any RBLs (black lists).

Use the Yahoo web directory when you want to find sites specializing in a given topic or you are looking for a specific Web site home page

Yippy queries several top search engines, combines the results, and groups similar results together into groups

Check any Internet host's reachability and how much latency there is in communicating with it from 50 locations worldwide

ARIN's WHOIS service gives contact and registration information for IP addresses, autonomous system numbers (ASN), organizations or customers that are associated with these resources, and related Points of Contact (POC). It doesn't include information on domain names or military networks.

Check a web page's reachability and response time from 10 locations around the world. See how long it takes to look up the site's IP address from DNS, to connect (latency from a location to the site), and to receive the page's text.

Ping is commonly used to determine if a given host is 'alive' on the Internet. It will repeatedly send a datagram to a network host to elicit a response from it and show you if, and how long it took to respond.

Query DNS domain name servers for information about host addresses, mail exchanges, name servers, and related information

Convert an IP address from 8/8/8/8-bit dotted-decimal format (dot-seperated, like 127.0.0.1) to 8/8/16-bit, 8/24-bit, and 32-bit notations in decimal, octal and hexadecimal.