Talking about other projects in a job talk I have seen plenty of job talks, but whenever the speaker talks about a list of topics that they are "not going to talk about today", I often get distracted and even a little bit annoyed. It dilutes the main talk contents, and I hardly ever remember what those items were. I understand that they want to show their breath, but it usually doesn't convey very well. Now that I am in that position, I am wondering if there is a good way to deliver the message.

What would be a good approach to briefly mentioning other projects that you are excited about?

Should I talk about them at the beginning or at the end? Is it a good idea to put all of the other projects under a single theme and not talk about the details at all, or should I try to explain each project's objective and approach? Should I talk about only a couple of projects or is 4 a better number?
The answer you need depends very much on how closely related your collection of interests are. What I did for my job talks was the following. I chose one of my topics that I knew would provide lots of pointers to my other ones. This way I did not just give a laundry list of "things I do" but rather at a nice point in the talk I could say something like "this raises two questions, the one I am going to talk about today is the first but I am happy to go into the second one privately later." The idea here was the other project came up when it made sense, indicated breadth (at least for my collection of topics), and did not feel overbearing. 

You mileage may vary but remember that you can choose which topic to give your job talk on and choosing the one that will give you the most connections to the others is as good a tactic as any.