The old town is small enough that you can easily walk the city in a few hours. However, if you want to get to some of the outlying areas and across the Khan river, you can rent bicycles from several shops and guest houses around town. The cost is generally around 10,000 Kip (US$1) a day. For longer trips to the waterfalls, some shops will rent motorcycles as well, for around $8 to $10 a day.
For journeys further afield, there are tuk-tuks - small three- and four-wheeled vehicles as well as many air-conditioned cars and vans for hire.