One of the more recent trends in weddings is to have a goody-bag for each kid who attends. Usually these bags have coloring pages, some candy and small toys to keep the kids occupied during all the "boring grown-up" stuff. If you want to go beyond the goody-bag here are a few ideas:
Have a special Kids Only area that is open for a few hours during the reception. For safety, create a sign-in, sign-out rule with the parents and the kids and only permit them to leave with the designated parent. In this area, have board games, coloring books, craft supplies, and goody-bags to keep the kids occupied. Find out if the venue has a television you can rent and hook up a Wii console for the older kids.
Chid Care Providers:
If you have any responsible, high school age attendees, ask them if they could be in charge of the kids area. Sweeten the deal by offering to pay them. If you don't have anyone that could be a sitter, look into babysitting services or home care services that offer babysitters. Make sure they come with good recommendations and are reliable!
Organize a wedding scavenger hunt. Separate the kids in several groups and give each group a disposable camera and a list of events during the reception. The first group to complete the list gets to take a special picture with the bride and groom, or gets a goody-bag.
Piñatas are always a fun event at any party. Make sure there is plenty of room in whatever area you designate since candy tends to fly everywhere!
If the budget allows, hire children's entertainment for an hour or two. Here are a few magicians I looked into in the San Francisco area:
If you can't find a magician you like, look into face painting, clowns, or puppet shows as well. If you have hired a photo-booth company for your wedding, have a specific time set aside for kids to use it. Have a chest with dress up clothes so the kids can get silly and have fun dressing up. As a craft, you can have them make a photo frame to hold their keepsake in. You can also have your DJ call up the kids during the cocktail hour and have a "kids only" dance hour with kid friendly music.
There is so much you can do for your kid guests to keep them entertained and have them remember your wedding as something very special!
If you have any other ideas you have used in the past, please post them here and share with all of us!