Another popular question of late has been, "since TripHub will no longer be available, can you point me to another online trip planning site?"
Again, there is no single, simple answer. What kind of trip? How many people? Do you know when and where you're going or are you looking for ideas? How complicated is your itinerary and will everyone be traveling together? Do you want to keep your plans private or share them with the world?
There are many online travel planning sites. Some new, some well-established. Each is different and each has its own strengths. There's also a host of collaboration and organizational tools that, while not specifically travel oriented, offer rich functionality.
So, with that caveat, here are some sites you may find helpful:
evite - While there are many upstarts competing for this business (MyPunchbowl et al.), evite remains the granddaddy of online invitation sites. It's not perfect, but it works and everyone knows how to use it.
Google Sites - Create a custom Web site for your group or event. Shared discussions, calendars, pictures, documents, privacy settings, etc. Or you might try a wiki or group organization site like WetPaint and Backpackit.
Groople - Group reservations and planning tools including room lists and payment collection from individual group members. Some suppliers such as Carnival Cruise Lines also offer online group reservation and planning tools for their customers.
TripIt - Organizes trip itineraries (flights, hotels and activities booked from leading online agency and supplier sites) and creates a private Web page with maps, weather, etc. that you can share with friends and family. Other sites (TravelMuse et al.) allow you and your group to clip, organize and share content and sites you find on the Web.
WeddingChannel - Offers free and fee based sites for organizing your wedding where you can communicate event details, collect RSVPs, recommend hotels, share photos, etc. Similarly MyFamily.com offers free and fee based family sites that may be useful for organizing reunions and vacations with extended family.
Yahoo Trip Planner - Explore and copy other people's trips/itineraries and create your own custom travel guide with hotels, activities, restaurants, maps, etc. that you can share with your group (requires Yahoo IDs) or the world. There are several other sites (TripWiser et al.) that allow you to build your own itineraries and remix those of others.
Clearly this isn't a comprehensive list. Feel free to add a comment and share your reviews and recommendations.