I was going to the USA for a medical observership program; my university was covering all my fees. I got a B1/B2 visa, good for 3 months, which included the details of where I was going and when. Because of some problems, I couldn't go, and didn't use the visa. Will that fact complicate my ability to get a tourism visa in the future?
There is no reason why an unused visa should cause problems. If anything, it's the other way around - an unused visa shows that you're not desperate to come into the USA (if you wanted to stay illegally, you would most likely use the first chance you got). Be prepared, however, to answer questions about your unused visa during any future visa interviews (or even at the border) - you should have a better answer than "there were some problems".