We have all been handed a promotional pen or coffee mug with a company logo imprinted on them from time to time.  The companies that create these items have an enormous variety of products that you can turn into a table favor or gift for your wedding party. By adding your custom artwork (a photo of the bride and groom or your names intertwined with the wedding date for example) for a one-time set up charge, you can turn an ordinary item into a keepsake that people can really use:
For a beach wedding, tuck a bottle of sunscreen, some sunglasses, and a rolled-up beach towel into a sand bucket:
For your bridal party, provide an tote bag with a sewing kit, compact mirror, travel size toiletries, etc:
For a table favor, colorful bags of mints are a nice choice:
The possibilities are endless!  I have personally used 4imprint.com to purchase many promotional items in the past and their quality and service are first-class.  They will provide free samples of most of their items if you want to inspect an item for color, size, and quality before ordering in bulk.
Using Promotional Products as Wedding Favors