At Ohio University the method of search box creation has been standardized in a simple format for LibGuides. Though if anyone here, in the library, asked for it I could create more custom search forms for specific disciplines. At the moment we are using one simple search per field. See the search box page as an example.
This way subject librarians who want to use the different search boxes can just copy the appropriate box to their LibGuide and change the content to suit their needs. A good example of this would be this english studies research guide that a colleague made for a specific class.
From a usability standpoint I think this is a pretty good model for opening up search boxes to every subject librarian in the college. There are two downsides... If there had to be any updates to boxes then the inheritance structure would not work. There are still many databases out there that can not be searched this way directly. Oh well I can still bootstrap by using Metalib if I have to. Hopefully when OhioLINK releases their new OSearch interface it will allow for direct searching. I also hope other database vendors will allow for search widgets.
I'm evaluating the construction of an engineering based research portal (similar to the engineering subject based research toolbar that I created for Mozilla Firefox.