Hi,
I'm wondering if there are any WYSIWYG-like editors for SPARQL, specially in javascript (preferably jQuery) so that it can be used in HTML textareas.
We use CodeMirror 1 with SPARQL highlighters. See this demo: http://codemirror.net/1/sparqltest.html. This javascript editor does a nice job of highlighting and auto-indent for SPARQL.
We developed a graphical SPARQL query builder for OntoWiki using AJAX and of course PHP for the plugin backend. It enables non-experts to create complex queries on a RDF-database. It is now a feature-rich but easy-to-use tool with a good work-flow and nice design. It has grown to 7500 LOC but its not slow at all and it uses modern technologies like SVG, jQuery and extensive use of Ajax (with JSON). It will be used (in the first place) at the history department of the University of Leipzig (Germany).
There are two SPARQL editors that I like very much, both of which are not open source so probably don't help you but I mention them to convey what I think a good SPARQL editor is like:
Top Braid Composer - with code completion on resources, syntax highlighting, SPARQL validation. written in Java using Eclipse framework.
AGWebView - browser based HTML widget, probably using javascript, syntax highlighting, SPARQL validation, etc. (check out the video for a glimpse)
Both products can be tried out using free trials. AGWebView can be tried out by downloading Allegrograph.