cardme is a Java library implementation of RFC 2426, VCard. It provides Java applications with a way to read and write from and to the VCard file format. The project's goals are to provide a flexible and easy to use library with excellent documentation.
IPNetwork is a set of utility classes for the .NET platform that take care of complex calculations related to networks, IP, netmask, CIDR, subnets, and supernets. It works with IPv4, has a light and clean API, and is fully unit tested.