Heather Carlson of Smitten with Italy is a great resource for travel to Umbria. She helps plan trips and also organizes tours—some designed around a festival with Letizia Mattiaci who runs beloved cooking classes in Assisi and was recently written up in the New York Times. Two such tours include one designed around Bevagna's storied medieval festival and another celebrating the olive harvest. Heather's website A Merry Feast is a treasure trove of how to get the most out of a trip to Umbria and beyond.
Madonna del Piatto is a gorgeous recipe and food website hosted by Letizia Mattiacci, author of the beloved "A Kitchen with a View" (look for it in while traveling in Umbria). If you really want to sink into the foodways of Umbria, I recommend giving her website a dive (but watch out, it's going to make you hungry). Letizia also contributes to a monthly magazine, An American in Italia, that is worth checking out for getting a rich understanding of the culture of the region. If Assisi is your destination, I'd recommend cooking and/or staying with Letizia at her B&B where she hosts tours (of particular note are her olive oil and porchetta trips), cooking classes, and welcomes travelers to her vacation rentals.
Life...Italian Style Jennifer is a professional chef, leading exceptional cooking classes and tours in Umbria.
Take Me Home Italy is an organization designed to connect people with their Italian heritage. Funny story, I connected on Twitter with the owner, and it turns out she and Keith and related! Small social-media world...
Winefathers is a fabulous concept—linking wine and Italy lovers with Italian wineries. Different levels of sponsorship include different perks. I have one of these on my Christmas wish list.
Italian towns have a Pro Loco, an organization that promotes the town's happenings. Wherever you are traveling in Italy, it's worth a virtual stop here to see what events will be in progress during your visit. Here's Spello Pro Loco.