Canvas 6.01: When I open it, I lose over 70 slots, and that is after having disabled 20-odd tools. (Anders Eklöf) [Another reader disputes this, claiming it only opened 4 files.]
Acrobat The worst offender I've ever seen is Acrobat 4.0 (not the Reader, but the full package). It opens 48 files by itself. Rick Zeman
Combining font files Since each font file in your Fonts folder contributes to your open files count, David Vasilevsky points out that you can reduce your open files total by combining font files and suitcases into a smaller number of suitcase files. He merged all of his fonts into just 5 suitcases. This reduced his open files total by around 100 files.
Virtual memory Also recall that, with virtual memory on, many files are counted twice.
Word Save bug is cross-platform Several readers noted that the problem with Word 98 and saving files occurs on the Windows platform as well.
Fast Saves work-around? Several readers have suggested that turning Fast Save on should eliminate the accumulation of Work files that lead to the Save problem. Indeed, Nick Van Valkenburgh points to a Microsoft document (Q233995) that states: "To reduce the number of temp files created, select the Allow fast saves check box on the Save tab of the Preferences dialog box. This should limit Word to one temp file created per open document." I have tried this and found that it seems to work on some days but not others. But if it works for you, great!
Update: A few readers pointed out that enabling Fast Save may lead to different Word glitches, such as bloated size of saved documents. Also, advice to turn on Fast Save to avoid the Save bug contradicts previous advice from Microsoft to turn off Fast Save (see this item). Oh well.
Equation editor Jason Kahn reported that the Equation Editor has a (possibly separate) problem with saving files: when trying to save a large document with an equation in it, you may get an error that says there is not enough space on the disk to save the file (another reader confirmed this).