"Numerous instructors, myself included, have found that lectures become more useful when students are forced to become active participants in the lecture." Read more from Roger Freedman, Professor of Physics, UCSB.
In her book Tools for Teaching, Barbara Gross Davis has many suggestions on dealing with various teaching scenarios. Here tips on dealing with a large lecture class are listed here: http://teaching.berkeley.edu/bgd/largelecture.html
Rich Felder, a well known Engineering professor at NC State writes: "...there are ways to make large classes almost as effective as their smaller counterparts. Without turning yourself inside out, you can get students actively involved, help them develop a sense of community, and give frequent homework assignments without killing yourself (or your teaching assistants) with impossible grading loads." Read his paper on "Beating the Numbers Game: Effective Teaching in Large Classes".
The SERC website has many resources for teaching introductory courses (especially Geosciences), but their general advice is applicable across any discipline: "Teaching large classes is particularly challenging, and newer faculty are likely to be assigned to teach at least a few of them. The resources below can help you keep your students actively engaged and minimize the time you spend grading, effectively and efficiently."
In addition to these links, feel free to explore the websites of other teaching and learning centers.