Siem Reap Transportation - Buses, Mini-vans, 4WD SUVs, Taxis
Angkor Tour Guide
Group#7, Phum Salakangseng, Khum Svaydangkum - (0)898 669
Transport and tours, with or without guide. Mr. So Sophea
24 Sivutha Road - 063 966 072
Scenic and charter helicopter flight services
Neak Krorhorm Express
#0003 Old Market - 063 964 924
Siem Reap to Phnom Phen daily van service
#14A Sivatha Blvd. - Tel - 063 963 662
You can buy your ticket from any tour company or guest house, just don't wait until the last moment , because you may end up sitting next to the toilet. Goes from Chong Kov Sou Bus Station (all buses leave Siem Reap from here), which is near the Phsar Leu Market in Siem Reap to the corner of Street 102 and Sisowath Quay (the river-side area) in Phnom Penh. Although I have to admit that I am not a big fan of buses in Cambodia and would rather take a taxi, I consider Mekong Express to be the best of the lot and worth the few dollars more that they charge.
Phnom Penh Sorya Transport
Center Market - Tel - 092 120 218
Also leaves from the Chong Kov Sou Bus Station in Siem Reap, but drops you near the Phsar Thmey Market in Phnom Penh, which is not really a convenient location, especially if you are staying near the river.
Virak-Bunthan Express Tour
Near Phsar Leu market - Tel - 015 958 989
This bus company would be my second choice after Mekong Express for trip to Phnom Penh and also drops you off at Sisowath Quay (the river-side area).