Running a travel agency is a good business, whether you are doing it online or offline. For one thing, it requires a lot less investment than many others. There are plenty of options too, like for instance, you can take flight, car, and bus bookings, allow hotel and home stay reservations, and provide bookings for activities such as water sports, adventure camps, walking tours, food tours, and many others. But you will have to promote your travel agency to have any chance of success.