I've release a new plugin called MTCgi.  It gives you access to parameters submitted by a form or on the url.  This plugin only makes sense in templates that dynamcally generate page from a CGI, i.e. templates used by mt-search.cgi, mt-comments.cgi, mt-view.cgi, etc.

One useful application is a General Purpose Search Template that retains all the settings that were specified in the form that invoked the search (i.e. IncludeBlogs, etc.) by adding the following into the search template <form> :

BTW, I'm open for other ideas that would be useful for this plugin (environmental variable, info about the client, etc.) without making it to complex (in which case you might as well use the PerlScript plugin).