Launching a Facebook app today, MyTab is a platform where friends can donate to your trip and you can book flights and hotels, while giving a portion to eco-charities. For now, the site is still restricted to travelers flying out of the United States. Since we last covered San Francisco-based MyTab, they’ve added a bunch of features to simplify your trip: you can estimate flight and hotel costs when you create an itinerary, browse special pages for vacations like weddings and celebrations, and (only on the Facebook app) check in to a city when you arrive. They are also building a young community by blogging about students studying abroad. Unlike some other travel startups, MyTab is facing unique challenges related to handling money. The site integrates with PayPal for donations, and the MyTab Facebook app is still waiting for approval to accept PayPal payments. They also have to follow US gift card laws: money can’t expire and legally belongs to users even if they leave MyTab, so the company must keep records and set aside funds. But I have a few gripes, as someone who’s been traveling for almost 6 months. First, flights and hotels come from Expedia, so you’re not necessarily getting the best rates (and the user interface is nothing to write home about). And second, you can’t seem to plan a trip with several destinations, so for a multi-city tour you’d have to add multiple trips. Challenges and gripes aside, a Facebook app is probably the best way for vacationers to reach out to their generous friends, especially since you can’t fund travel on sites like Kickstarter. All those trip-planning startups are useless if you don’t have enough money for a trip, so MyTab might consider partnering with them to reach more would-be travelers.