SiSU provides a lot of "plumbing" and is readily usable as a tool by those comfortable with marking up documents with an editor. The syntax is fairly easy to learn, especially the subset required to start using SiSU effectively.
SiSU might also be of interest to developers interested in:
experimenting with the search implications offered
producing additional output formats
producing conversion tools
producing input interfaces, (experimenting with additional interfaces for producing sisu source documents)
Several tools that are of interest would come under the heading interface and conversion. Amongst others, the following are of interest:
Converters from various document formats, such as Open Document Text (ODF), MS Word(TM) and Word Perfect(TM), even html. The problem here is one of the most important things for SiSU is to be able to recognise the structure of a document, and many documents prepared in other formats have not been prepared strictly with a view to representing structure, but appearance - so heading levels may be "painted" to look right rather than have the correct structural representation. Even if conversion is not perfect this may serve as a first step in assisting in conversion of documents to SiSU for those with legacy document sets that they would like to have in sisu format. (once in SiSU it is easier to get out in various other formats as this is what sisu does, within the constraints of the information that sisu uses to generate output)
The possibility to save directly from from various word processors, and possibly templates within them to assist in making sure the document structure is "understood" by SiSU.
Web interface/front-end, a form like front end for the writing or submission of sisu documents to a server which uses SiSU to generate output. Headers could be made available as separate small entry forms with help provided to explain where they might be used. Apart from the most important headers such as title, author, date and possibly subject the remainder of the header forms could be placed after the form for substantive content. This would offer a more Web 2.0 like approach to the use of SiSU and the possibility of using it for collaborative editing of content (possibly for documents that are to be finalised/published as the citation system is most suited to published works). [Collaborative editing is currently possible through use of a collaborative editor such as Gobby which makes use of the Obby protocol].