Here's another convention booth idea to think about. It's a bit more on the technologically challenging side, and could be a bit pricey depending on how big you want to go with it.
Before I get to the idea itself, let me prep you with some background thinking. One of the primary reasons for getting a con booth is to sell your wares. Why would they buy from you at a convention instead of online? Several reasons. They might want to save on shipping costs. They might want an autograph or a sketch. They might want a con exclusive. They might never have heard of you before and just discovered you as the walked by your booth. But ideally, what you provide them with the sale is a personal experience. They don't just walk away with your book, but they walk away happy that they got your book because you were also really cool to talk to and they have an anecdote along with the book.
Background, part two. One of the methods marketers use to promote their products is to highlight how others have already gotten it. There's two angles to this, actually. If they get celebrities to endorse a product, then the hope is that you will think you can be more like the celebrity if you use the same product they do. The other option is to demonstrate that a lot of people are already using it, and it's popular, and you should use it to in order to be part of the in-crowd.
You're doing three things with this. First, you're providing an additional connection with the people who buy your work. They've got a story with you (not just about you) and are more likely to become deeper fans. Second, you're showing everyone else how popular you are and how they're not part of the in-crowd unless you buy your stuff. Third, the constantly changing images on the screen is simply eye-catching, and people will wander over just to see what it is.
(Potential fourth benefit: get the person's email address so you can send them a copy of the picture... and add them to your mailing list!)
The technology for this shouldn't be too difficult to overcome. If you had the screen hooked up to your laptop or iPad, just running a slide show of all the images in a given directory, you could just Bluetooth new pics from your phone directly into that folder. Or if you've got a dedicated camera, you could transfer them periodically using an SD card (or whatever your camera uses). The software is at a point that it shouldn't too burdensome to figure out how to set this up, but some of the specifics might make this tricky depending on the specific types of devices you're using.
The cost of getting a decently-size TV/monitor is certainly one prohibitive cost, but shipping it to the convention site is another consideration. And you'd also likely need a dedicated mounting system for it, which are readily available but not terribly cheap either. Because of that, I wouldn't expect too many people would opt in for an idea like this... but that would make it all the more interesting and eye-catching to the general con-going audience.