Actually, Formulate Pro is out that does all this and more:
http://code.google.com/p/formulatepro

This is really, great. I'd like to be able to drag an image of my signature onto the document, but this does text forms just fine.

I would say it is pretty effective as well. Just needs a good icon and the dev needs to fix some little annoyances with it. All the features mentioned below would be great, but as it stands I'll continue to use it.

With just a few small improvements (the ability to change font and size, some simple zooming options, a slightly better "save" format, and a more intuitive workflow) everyone would want to use this. As it is now, it's very effective, and I use it all the time.

i concur with kadis.. this needs some cleaning up, but it does the trick. kinda cool that you can change the font and place everything where you want. not so cool that if you do a typo you have to start over. but ya got to give it credit, at least it's free. :)

This is a great app. There's been many times when I've need to add text to a pdf and now I can, for free.

I wish that this was more of a finished product, but it works, and I don't know of any other program that does this.