There isn't much shopping on Tortola so don't expect it to be like St. Thomas if you go. This is a good thing because it makes you focus on taking lots of great pictures to capture all of that natural beauty to take home with you as a souvenir. We highly recommend visiting the artist David Thrasher, who has a gallery behind Coco Plums restaurant. We bought several of his prints to adorn our new home and the remind us of our honeymoon every time we look at them. Soper's Hole has some specialty boutique-type stores that had some great gift items and souvenirs.
Take home some hot sauce for those people in your life that are convinced they can handle anything hot. They will change their mind.
We also made it a goal to buy a t-shirt from each of the islands we visited. Foxy's on Jost Van Dyke is the legendary bar featured in many of Kenny Chesney's songs. They had the biggest selection of clothing by far and lots of Foxy's/Jost Van Dyke souvenirs. Foxy's Taboo (further around the island) is much smaller so don't plan on buying much there. There isn't much else on the island though!