Use Easy Feed Editor to create your own feed. Easy Feed Editor supports both RSS and ATOM.
XTR (XML Transformations) is project that allows you to transform, merge and summarize XML files basing on XSD files and mappings. Generates XSD file form XML (XML2XSD). XML editor with formatting capability, XSD visualization using tex, XML Validation.
GNOME/GTK+ Feed Reader
Note: Liferea has moved to Github. Please check out https://github.com/lwindolf/liferea
PITy is a collection of Polish tax forms in SVG format with acompanying simple software to fill forms with data.