From FullScope Solutions:
xCELLgeo is an Add-In that allows users to perform a number of useful functions on IPv4 addresses. Specifically, users can: 1) Convert dotted IPv4 addresses (e.g. 192.168.1.1) to their decimal format (e.g. 3232235777), 2) Convert decimal IPv4 addresses to their dotted format, 3) Perform reverse DNS lookups on IPv4 addresses, and 4) Utilize GeoLite data created by MaxMind to determine country and city based geo-location information about an IPv4 address. This software does NOT include the GeoLite databases as part of its distribution. Users are required to download and import the databases independently from MaxMind (http://www.maxmind.com) in order to utilize these features. Functions are provided via ribbon buttons and as user-defined functions allowing maximum flexibility. If you need to perform analysis on IP addresses within Excel or are looking for an easy way to convert IP addresses from decimal to dotted format and back again, xCELLgeo is the tool for you.