For this week's roundup, I thought we'd put together a list of some cool planning tools that are making use of the latest technologies to help you plan your wedding. If you know anything that should be in this list that I've missed, please post in the comments!
Olivia Luca Design Studio This Portland-based design firm has an addictive Flash tool where you can
design your bridesmaids' dresses from silhouette down to the sash and the trim. Eco-friendly fabric options are available for order as well, or you can be like me and just keep making tons of dresses online and daydreaming about the fetes I can wear them to!
Wedding Gown Guru I met Bridgette, the "Wedding Gown Guru" , on twitter.com and took a look at her interactive gown selection tool. Simply answer a series of questions about your style and personality, and she will suggest several different looks for you! Much more fun that a visit to a crowded bridal salon, and a great way to prep yourself before going out to shop in person.
David's Bridal "Dress Your Wedding" Thanks to Sasha Souza, celebrity planner and the brains behind Sparkliatti, for turning me on to this. They have done a great job in creating a Flash tool that allows you to mock up your bridesmaids' gowns and colors, plus groomsmen's attire, so you can preview the lineup of your whole virtual wedding party, including groomsmen and child attendants!
Calculators at Eventageous Eventageous is an Austin-based event planning firm, and they've been on 
the cutting edge for forever. I know this because they've had these great calculators on their Resources page since I started my business in 1999! Scroll down this page to see the Calculators; here, you can tote up everything from the number of people that will fit into a given square footage, to a sample wedding budget. Simple tech, but so helpful!
Wedding Mapper So many weddings involve out of towners, so this interactive mapping tool with great design is a must. You can even tag the locations with your notes ("Here's where he proposed to me"/"This is our favorite bar"). Also included is a method for leaving and reading reviews of vendors.
Backpackit.com Not an exclusively-wedding tool… Nonetheless, Backpack, the consumer version of design 
powerhouse 37signals' Basecamp, is inexpensive, easy to use, and a great way to invite collaboration across a large group (think Mother in law, mom, bridesmaids, dad, the groom, and your wedding planner!) I'm currently using it with a client and love it — we might even make it part of our standard package in the future.
Evite Drink Calculator Most of us have used Evite for their free online invitations, but I recently discovered their handy-dandy drink calculator. It's not super detailed, but it at least can give you a place to start, if you have no idea where to begin as far as beverage purchases.
Hope you find these helpful!