Many are wingless, which makes them somewhat amenable to handling, although one must be very gentle if handling these interesting creatures. They require a fairly warm habitat and high humidity level, and a sizable stick on which to crawl around. They are carnivorous and very adept hunters, so will need to be supplied with a source of live prey - small insects such as aphids to begin with, but as they grow they will tackle large prey. More information on these insects can be found on G.J.L. Ramels Care of Mantids page. Tarantulas can often be found in pet stores.
Tarantulas are venomous, but many species produce no more of a reaction in people than a bee sting.
The degree of reaction will vary with the species, the person, and the amount of venom injected. There is a danger of having an allergic reaction to the venom however, including anaphylactic shock. There are several hundred species of tarantula, and some are more aggressive than others. Care is required when choosing a species and handling tarantulas, and a potential owner must be sure of what they are getting. A reputable breeder or source will help decide on an appropriate species and educate an owner on care and handling.