1T3XT offers a suite of products that are useful to create and/or manipulate documents, more specifically PDF and RTF documents. There's some support for XML and HTML, but this isn't the core business of iText.
`ABL' is a basic flexible abstract list library defined using C preprocessor. It allows you to define linked lists of arbitrary types very easily. You also can use it as stacks and queues. You can easily define complicated types like list of lists etc.
At4J provides Java support for reading and creating Zip and Tar archives. It also comes with third-party compression libraries for bzip2 and LZMA support. At4J supports more Zip capabilities and compression methods than Java's built-in Zip classes, such as Unix file metadata and bzip2 compression.