Until the Cat finds and stickies the master cheat sheet, here's the one I used. Note that I made it when I had Word 7, then updated it for Word 2002 and later Word 2003. If you run a newer version, some of these may not apply.
Block Protect Paragraph: select, Alt+O, P, Alt+F, Alt+K, Enter (Format, Paragraph, Text Flow, Keep Lines Together, OK) (see also Keep Text Together)
Bold, start or stop: Ctrl+B
Center: Select text, then Ctrl+E
Change Margins: File, Page Setup (among several methods)
Characters, foreign, mathematical, typographic: Alt+I, S (Insert, Symbol)
Comment, Create: Alt+I, A, type comment text, Alt+C (Insert, Annotation, type text, Close)
Comment, Edit: Alt+V, A, change text, Alt+C (View, Annotations, change text, Close)
Comment, View: Alt+V, A (View, Annotations)
Copy: highlight, Ctrl+C (see Paste)
Copyright symbol ©: Ctrl+Alt+C
Cut: highlight, Ctrl+X (see Paste)
Find: Ctrl+F
Flush Right: Alt+O, P, Alt+I, Alt+G, (Format, Paragraph, Indents and Spacing, Alignment, Right)
French é (accent aigu): Ctrl+’+e
French î (accent circonflex): Ctrl+^[Shft+6], i
Go to Page X: Ctrl+G, X
Hanging Indent: Alt+O, P, Alt+I, Alt+S, scroll down, Enter (Format, Paragraph, Indents and Spacing, Special, Hanging, OK)
Hard Hyphen: Ctrl+Shft+hyphen
Hard Space: Ctrl+Shft+space
Header, Create: Alt+V, H, type text and/or use Page Number button, Close (View, Header and Footer, text, Close or “x”)
Header, Edit: Alt+V, H, edit text, Close (View, Header and Footer, edit, Close)
Header, None on Page 1: Alt+V, H, Page Setup (View, Header and Footer, Page Setup)
Indent: highlight, Tab
Italics, start or stop: Ctrl+I
Keep Paragraph Together: select, Alt+O, P, Alt+F, Alt+K, Enter (Format, Paragraph, Text Flow, Keep Lines Together, OK) (see also Keep Text Together)
Keep Text Together: select, Alt+O, P, Alt+F, Alt+X, Enter (Format, Paragraph, Text Flow, Keep With Next, OK)
Keep Words Together: see Hard Space or Nonbreaking Space
Make It Fit (reduce number of pages or one page): Alt+F, V, “Page-Arrow” button (reduce number of pp) or “Page” button (File, Print Preview, Shrink to Fit)
Nonbreaking Hyphen: Ctrl+Shft+hyphen
Nonbreaking Space: Ctrl+Shft+space
Paste: Ctrl+V
Paste Special: (Pastes HTML/Internet text to word processing) Alt+E, S (Edit, Paste Special)
Print: Ctrl+P (shortcut to File, Print)
Replace: Ctrl+H
Save: Alt+F, S, [type name], S (File, Save, [type name], Save)
Save As: Alt+F, A (File, Save As)
Select All (highlight everything): Ctrl+A
Shrink to Fit (reduce number of pages): Alt+F, V, “Page-Arrow” button (File, Print Preview, Shrink to Fit)
Spellcheck: F7
Thesaurus: Shift+F7
Underline, start or stop: Ctrl+U
View Comments: Alt+V, A (View, Annotations)
View Paragraphs: Ctrl+* (Paragraph button)
View Tabs: Ctrl+* (Paragraph Button)
Word Count: Alt+T, W (Tools, Word Count)
On a lot of these, there's more than one way to execute the same command. As a leftie whose mouse is on the right, I tend to gravitate toward keyboard-based commands rather than mouse.
Hope some of it's useful. You'll find you memorize the ones you use often pretty quickly, but there are a few things I still look up.
Maryn, whose computer is getting old but still runs fine