With growing concerns about security, you'll be hearing a lot more about digital surveillance systems. A company on the leading edge is Ottawa-based March Networks, which makes digital video recorders used to store and manipulate the images captured by cameras. The company's stock is red-hot, having doubled since Halloween. The company's technology is resonating with banks, retailers looking to deal with false "slip and fall" lawsuit claims, and transportation systems such as subways and railways. For more on March, I have an investment feature in today's National Post.