A: Heck, yeah! Every area is different, mind you, but you can always count on two times of year for a surge in selection and awesome-ness at thrift stores. The first is in the spring when folks are doing their annual cleaning at home and unloading all kinds of stuff from household appliances to clothes that no longer fit. The second is right after Christmas when folks are cleaning out from the holidays and making room for the influx of new toys and gifts.
Just like with regular retails stores, it's always best to shop of season in thrift stores. Looking for a winter coat? Do so during the summer? Looking for outdoor sports equipment? Do so in the winter. Selection will be higher while demand and prices will be lower.