Here are some "FREE" (this guy is a believer in open soruce stuff). Guitar lessons that help you develope a STRONG strumming rhythm.
<a href="http://www.archive.org/details/folk.guitar" target="_blank">http://www.archive.org/details/folk.guitar</a>
I've been playing the guitar for 40+ years and I learned a lot from watching him. He makes strumming the guitar a "blinding glimpse of the obvious". Shows a little blues... a little folk etc. His concepts on rhythm are that each person should develop their own strum patterns, but there ARE some basics.. From there one can expand.
I ran into his stuff when I was learning to play the banjo, believe it or not (he plays both - and gives a little harmonica lesson in this series, too). He has a couple of free books online, too (you can buy them -- I did, 'cause I can't take my computer into the bathroom <img src="images/smiley_icons/icon_redface.gif" border=0 alt="Embarassed"> ).
His site is the HOW and TAO of Banjo and Guitar at:
<a href="http://howandtao.com/books/book-index.html" target="_blank">http://howandtao.com/books/book-index.html</a>.
Check it out.
Good luck and good licks.
<font size="1">Boredom is a personal defect.