Several tour companies in Trujillo  cover the city, Huaca de la Luna  y Sol, Chan Chan , and even El Brujo . The best of these are Guia Tours (Independencia 580, tel. 044/23-4856, guiatour [at] amauta [dot] rcp [dot] net [dot] pe, US$8–12) and Colonial Tours (Independencia 616, tel. 044/25-8261, daily, US$5–8), which is based out of Hostal Colonial.
If you prefer a personal tour, Benito Jáuregui Rosas (Pizarro 318, tel. 044/957-6409, guiabenitojauregui [at] yahoo [dot] es) gives thorough tours in Spanish; Carmen Linares Santos (tel. 044/930-7177, karmelinsa [at] hotmail [dot] com) is fluent in English; and Michael White (Cahuide 495, tel. 044/966-2710, casadeclara [at] yahoo [dot] com) tackles both of those languages, plus French, Italian, and German.