Often, hard questions are only hard b/c of a lack of background info. You get a little background (or a refresher) and you're ready to find our holdings. So a guide made by us isn't an absolute requirement, although having one made with our call numbers and locations is handy. But, how do you find a guide if not on our site?
You have a couple of options. There's the GODORT Handout Exchange first and foremost: http://www.lib.umich.edu/govdocs/godort.html.
If that doesn't yield results, there's always Google. Just be sure to add the term "guide". You might also want to add the term "library". Sometimes it helps to limit to site:edu, but I'd be careful about that. You'll miss a lot of good stuff coming from public libraries and professional organizations. Plus, for legal research, law firms sometimes put up useful information and they're typically *.coms.
For example, say you need some background on documentation on U.S. treaties. At the Handout Exchange there are 7 guides listed (http://www.lib.umich.edu/govdocs/godort/subjects.htm#treaties), but the most recent listed is 2004. On the other hand, a Google search of "treaties library guide" (http://www.google.com/search?q=treaties+library+guide) results in *tons* of current results with #7 from Columbia (http://www.law.columbia.edu/library/Research_Guides/internat_law/treaty_research) being particularly appealing to me. --Amy