[whpalmer4]

Have Excel print the spreadsheet as PDF, then insert the PDF file into OmniFocus. If you have your print dialog expanded (click on the triangle), there's a PDF button that gives you all sorts of options other than defacing a nice sheet of paper...

If you aren't syncing OmniFocus, you could set up some Rube Goldberg scheme where instead of embedding the PDF files into OmniFocus, you just link them (which is the default behavior). No difference in appearance, but the files could then be updated periodically by some means, and OmniFocus would simply show you the latest version when you opened the note. I rarely use Excel, so I don't know what automation facilities it provides, but if there are some, you could presumably use them to update your various "display" documents periodically (or each time you change them) so that the copy displayed by OmniFocus would be up to date.