Forms
One aspect of forms that is kind of interesting is that a PDF "form" is really a bundling of an application, and the data that the use is creating with that application. I can't think of any other mechanism that merges these two things.
Traditionally a form is a request for information. You get a form to fill out to enroll your children in swimming lessons. You get a big honkin' multi-part form to fill out to do your taxes, or to make an insurance claim.
A lot of people build their forms in Word, or InDesign, or some other tool that focuses on the look of the form. That's fine if your goal is to make a form that users can print out and fill in, or use the Typewriter tool in Acrobat to type onto to fill in (that's a very handy feature), but there's so much more you can do.
A PDF form isn't just the presentation - what the form looks like. It's also a container that stores the data you fill out in the form, so that you can email the form back to someone, submit it over the web, or even print it and mail it back (with a barcode generated on the form so that smart software on the other side could retrieve the data from the form and put it into a database without someone having to type it in).
And it's not just those two things; it's also logic. Does your swimming lesson form have fields where you can type in the children's names? If the parent indicates they have two children they would like to enroll, then you can make the form "invalid" (and not let submit it) until the names of those two children are filled in. And also update the price to reflect the discount for having more than one child from the same family. Nobody likes having a form sent back to them asking for more information, so helping your users fill in forms and submit them only when they're properly filled in is a big win.
One of the reasons I'm writing this post is I was doing some googling for simple terms that someone might use when they want to create a form, like, "create a form", or form create and I was very surprised to see that PDF forms don't show up at the top of the list. We've got a great solution to this problem, that's being used for a huge number of forms, both online and offline, and yet we're not the first thing you'd find if you were a user trying to figure out how to make a form. Heck we're not even on the first page of Google results, which means we're essentially invisible for those terms. Even for the term form design, which has part of our product name in it, we're about halfway down the results page.
Part of the reason we're low on Google Juice could be the product name. "LiveCycle Designer" doesn't scream forms, does it? And another part is that we don't really promote Designer as a standalone product, because it comes with Acrobat Pro and with LiveCycle ES. Acrobat Pro also comes with the CS4 so you get Form Designer with that as well. In fact, if you've got Acrobat Pro, you've got two ways of designing a form: Acrobat itself, which is good for simple forms, and Designer, the dedicated form design tool. So it can be a bit hard to stumble onto Designer unless you already know what you're looking for.
And hopefully, this blog post will do it's little part in helping it be what you're looking for.