We had 19 guests at our wedding at CSA in '06. Gave each of them (or in the case of couples, each couple) a small souvenier photo album filled with pictures from the ceremony and other pictures from the vacation which they were involved in. We also inclued a CD with all the digital photos we and our guests took while we were there. And for a couple of very close family (Grandma, Parents etc.) we also gave them a copy of the DVD.
I have 24 guests coming to our wedding and I have a goodie bag with 6 different beach/travel themed gifts. I know it may seem like a lot but I truly appreciate them coming to another country to celebrate our wedding with us! I got great deals and favors on www.pricewisefavors.com. Always google coupon codes for online stores, even free shipping will help.
I got some nice fans (b/c it will be hot), a beach themed photo book, a 3 tiered wedding cake candle with seashells on it, "love" coasters, luggage tags and mini drawstring beach bags that I will fill with something sweet! I know a lot!!! LOL!
If you make a CD of music for the ceremony - you could give copies to your guests. You can make your own envelopes (with a pic of you, or your names & wedding date) to slip the CD's into... here's a template for one. http://www.fractalfairy.com/cdtemplate/index.html
You could use the CD idea for almost anything... pics of people who will be attending the ceremony, or of the two of you through out the years of your relationship... and so on...