General information:

http://en.wikipedia.org/wiki/Budapest

http://www.lonelyplanet.com/worldguide/hungary/

http://www.hungarytourism.hu/main.php?folderID=879

http://www.funzine.hu 

Sights in Budapest:

http://www.budapestinfo.hu/en

• Buda Castle
• Chain Bridge
• St. Stephen's Basilica
• Parlaiment 
• Matthias Church
• Heroe's Square
• Citadel
• Fishermen's Bastion
• Thermal Baths 

Accomodation: 

http://www.budapesthotelreservation.hu/index.EN.php  

Map of Budapest:

http://www.utvonalterv.hu/

Budapest Public Transport - http://www.bkv.hu/english/home/index.html