Mallaig is a small fishing port on the west coast of the Highlands of Scotland. It sits at the end of the A830 "Road to the Isles" (http://www.road-to-the-isles.org.uk/) from Fort William and the Fort William - Mallaig branch of the West Highland Railway (Glasgow - Crianlarich - Oban & Glasgow - Crianlarich - Fort William - Mallaig). It's also a relatively busy passenger ferry terminal, with multiple daily Caledonian Macbrayne (http://www.calmac.co.uk/) sailings throughout the year to Armadale (on the Sleat Peninsular of the Isle of Skye) and the four Small Isles (Eigg, Rhum, Canna & Muck).
As such, it is not so much a tourist destination, but a useful stopping off point for many journeys to and from the islands. Holiday makers heading for the islands use the shops to stock up for self catering breaks, and the town's two main foodstores (the Spar & Co-Op) can take telephone orders, pack groceries and send them by ferry to the smaller islands that have no shops of their own. It's also a great place to enjoy a bag of fresh fish and chips.
There are up to three train services a day from Glasgow Queen Street or Fort William (http://www.firstscotrail.com/), with the most services during the busy summer season. During the summer the West Coast Railway company operates a daily steam train called the Jacobite that hauls a rake of preserved carriages from Fort William (http://www.steamtrain.info/) This is the same train and railway line made famous most recently by the Harry Potter films. In Fort William you can connect to Scottish Citylink (http://www.citylink.co.uk/) buses to Edinburgh, Inverness and Glasgow, and nightly (except Saturday) Caledonian Sleeper train to London Euston.
Ferry services to Armadale are frequent, but services to the Small Isles are less so, especially in winter when some islands are only visited three times a week. Careful planning is required if you want to arrive by train or bus and connect with a ferry, although most printed CalMac timetables include times of connecting trains to and from Fort William and Glasgow. Those heading for the Small Isles from Glasgow should note that there is only a connection between a train from/to Glasgow and the ferry on a Saturday during the summer, and no connection at all during the winter. You will need to stay overnight en route, most probably either in Fort William or Mallaig. There are, however, many B+Bs in the town and an excellent small hostel (http://www.mallaigbackpackers.co.uk/) near the station.
There is, additionally, a bus service from Fort William and a bus service to Oban (http://www.road-to-the-isles.org.uk/westhighlandflyer.html), which is considerably faster than backtracking inland by train. For bus info, see http://www.road-to-the-isles.org.uk/transport.html For scheduled train info see http://www.firstscotrail.com/.