Most hotels and guesthouses can organise car hire for the day, with a going rate of US$20 to US$30. Upmarket hotels may charge more. Foreigners are forbidden to rent motorcycles in and around Siem Reap. If you want to get around on your own motorcycle, you need to hire one in Phnom Penh and ride it to Siem Reap.
Some of the guesthouses around town hire out bicycles, as do a few shops around Psar Chaa, usually for US$1 to US$2 a day. Try to support the White Bicycles (www.thewhitebicycles.org) project to help the local community.