TrainWorld.com offers HO train sets by numerous manufacturers, including sets that feature Thomas the Train, historical trains and starter sets. The sets allow one to set up a track and operate a train right away.
Sets from major manufacturers such as Lionel and Ahearn are available. Some sets are based on popular shows such as "Thomas the Train" and "Wilson's Freight Adventures." There are also sets based on trains that used to be in service, such as old steam-powered trains. There are sets modeled after Amtrak passenger trains, as well. A train set can match a theme or get a person started on a hobby or collection.