Not that I want to contradict Greg, but there are ways to do equity incentives even in LLCs. The key term you want to search for is "Profits Interest". A good (though rather old) blog post about it is available at http://meetkendall.com/2009/12/06/sharing-equity-in-an-llc-profits-interest/ and you'll find some other information online, including some written by lawyers (such as http://www.strasburger.com/bios/bio_pdf/Browne-Equity_Incentive_Comp_Plans_for_an_LLC.pdf ). Note that it looks like your LLC tax election (partnership or C Corp) does matter, but I don't know enough to tell you why and how.
IMHO, the main issue you'll face is that most lawyers are not very familiar with those types of plans, so you'll probably have a hard time finding one who will be able to get the legalese absolutely right. In most cases, lawyers (and accountants) prefer to go the easy route, which is to set up a Delaware C Corp, because they know the process fairly well. I, too, have an LLC, so I've had some interest and had my wife (who's a lawyer) worked on a modified Operating Agreement that has a Profits Interest plan. But... we never completed it and I resorted to a verbal agreement with my advisor (for whom I wanted to set it up). That said, it's definitely an open issue for me as well and as I look to hiring people full-time, this will become a more pressing matter.
You might also want to take a look at the Grunt Fund model and read the Slicing Pie book (www.slicingpie.com ), which addresses how to compensate contractors for their work and grant them rights to equity once it's formalized (such as when you convert your LLC to a C Corp, which you'll probably have to do at some point, especially if you plan to raise VC funds).