Ask HN: Is seeking a patent for a web service worthwhile?

I'm 90% done the features of a web app that I'm really quite excited about. I only have a couple of things to finish up before I'll be posting up a Beta for you all to play with. One of those things, at the insistence of several non-tech but lawyerly family members, is to explore getting a patent. I rather dislike software patents because I feel they're ripe for trolling/squatting, stifle technological improvements, and I think code resembles more a recipe (non-patentable) than an invention. That being said, I'm alive in a world where software patents are real, and my dislike for the possibility of somebody stealing my beloved idea [and especially implementation of it] is greater than the grudge I hold against software patents.

The technology in question is a customizable toolbar that installs as a bookmarklet. I'm not comfortable explaining what the toolbar does, but rest assured that it's very, very useful, and definitely a novel idea. The closest thing I've seen to it is Quix [1], which leaves much to be desired. What I've made is a remarkable feat of CSS/JS hacking, and I don't want it to be stolen.

Aside from the obvious advice of "ask a lawyer," I'm looking for advice about the following:

1) Assume my App was "Quix" (with some very unique twists)... would it be patentable? Would it be worthwhile, IYO, to patent it? (Subquestion: How much protection would a patent grant; could somebody copy it and modify something slightly?)

2) Assume I did want to seek a patent, how much of the product could I expose right now? Could I still launch a "Beta" or would that be putting it in the public domain? How about a video?

I realize the likelihood of this idea being a measurable success is slim... says you. Yet, I cannot help but be optimistic about it. I've demoed it to several family & friends (of varying tech-savviness) and while some are indifferent (but see the value), the majority are excited about it and can't wait to start using it.

Finally, thank you all very much for taking the time to help me in what feels like a pivotal point in my life.

[1] http://www.quixapp.com