If I got one of these cards my day would certainly be brightened. What a cheery little crew of friends! Thanks anonymous future friend for sending me a note!
Available at: Suck UK http://www.suck.uk.com/product.php?rangeID=154&rangeNew=1 ($16)
This is the perfect card to thank a friend for a lovely dinner party. Look how happy that cat is to have eaten such a delicious meal!
He doesn't really look like he wants you to have a nice day, but the sentiment is there.
Available from: Sharif http://www.etsy.com/listing/39809663/i-heart-you-24x7
Available at: Thinkgeek http://www.thinkgeek.com/homeoffice/supplies/e5da/ ($10) Via: Cubicle Bot http://cubiclebot.com/office-supplies/floppy-disk-sticky-notes/