You've pretty much exhausted your options, as far as I can tell.
Snapshot Viewer allows you to view a point-of-time report, with all Access formatting and tricks in place. It does require a small download the first time you use it, but after that it will work on that computer from then on, like Acrobat or any other executable. Why does this not fit your needs?
Publishing with Word/Excel, as you've found, creates an .rtf file that loses some special Access formatting. On the plus side, it doesn't require an additional download for 95% of people.
If you need your data to be malleable, you may want to use a Form instead of a Report. Have you looked into the Access Developer's Runtime version? It allows you to run Access files, but not change design, and it is less able to handle run-time errors (i.e., not at all).
I don't know if there are any Access->XML programs out there, but they might be able to convert MOST of your report into a usable, webpublishable report. You will likely still lose some formatting. You did say you didn't want to use any sharewares though, so I'm not sure what else there is.
David R