I have always been a strong believer in active learning, even in huge lectures. One of the main ways I'm incorporating active learning this term is through peer instruction and Poll Everywhere (an all-software version of clickers). Carleton has a paid account for Poll Everywhere that all professors are able to use, and the service is totally free to students.
So far, even though not all my questions have been perfect, I am quite happy with the results. It seems that students are engaged with the questions at hand, based on my walkabouts and seeing much arm waving toward the screen as students discuss the answers. In most cases, I see a marked improvement in how many are selecting the correct response.
Here's a good example. In my Processing class, I asked the following question after we learned about variables:
At first, the answers were pretty evenly split between red (52), blue ( 46), and neither (42). After students had a chance to discuss with their friends ("convince someone who answered differently than you why you are right"), the responses were mostly red (77), still some blue (24), and fewer neither (15).
Even better, after the voting, I ran the code so we could see that the answer was indeed red, and I said "I guess you want to know why, right?" There were students who audibly agreed with that sentiment. ;) So I did an explanation on the black board using our variables-as-boxes analogy. It was wonderful.
I have only done five "real" polls between these two classes so far, but I must say that I am already a strong believer. It will be interesting to see what students think of it when I ask for informal, anonymous mid-term feedback in a few weeks.