Monkie makes AWESOME packages.
That said, I've done the following:
~Hand-painted small flower pot, small baggie of organic soil, forget-me-not seeds.
~Word games (large print, har har) books, a really giant pencil, and a bookmark.
~Assorted teas and/or coffees, a hand painted mug or funny one, and the Splenda packets with sayings on them.
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Bittersweets, a box of kleenex, chocolate, and a good book for a friend who was recently post-breakup.
~Raid on the $1.00 travel size bins at Target or Walmart to make a pamper-box.
~Small canvases (2" x 2") painted with single words that were inside jokes. I did pairs of four or six.
~Microfleece blanket, thick socks, can of Muir Glen chicken noodle soup, a beanie, and mittens for a sickie friend up north.
~Funnily decorated flip flops (glitter, FTW!), tube of sunscreen, funky sunglasses and a cheesy visor for one of my snowed-in friends.
I used to collect little things that were on sale or whatnot at Ross or Michaels, etc, whenever I went out and about and at the end of a month, I'd tuck the randomness in a box and mail it out just for a smile. Things that reminded me of that person, greeting cards that would crack me up (and sent blank ones for her to send out), etc. It's fun.