The edmunds forums (prices paid and buying experience) have separate forums for leasing experiences for each car. They provide a great deal of information on the current money factors and residuals as well as the prices people paid.
If you're looking for the best deal, find a car that is being offered with a special money factor (see links below). The money factor is the financing rate used in the lease calculation. The lower the better. (I just got a Venza --- money factor was .0005, which is equivalent to 1.2% financing). With the money factor in place, you negotiate the purchase price as low as possible.
Also, you should consider fixing your out-the-door payment (e.g., $1,000) when you compare offers. Simply tell each dealer that's what you want to pay out the door. The out-the-door numbers used in advertising are random and created only to get the monthly payment at a nice looking number. You can put down more or less and get the same deal with only the payment increasing or decreasing based on how much you put down (it's usually around $30/mo per $1,000 down). There is no fixed amount you must put down (although dealers may require you to cover registration fees, etc up front). The common belief is to to put as little down as possible in case the car is stolen or totalled b/c you may not get back what you put down.
Below are some helpful links. I've also attached an awesome excel spreadsheet I created to negotiate my lease in June 2010 (a 2010 Venza). Supposedly, there's an ipod app too for $4.
. (the awesome edumunds forums)
(shows the financing rates for leases for almost all models --- they've already converted the money factor to an interest rate by multipling it by 2400).
(another site that lists special lease rates for certain models).
(links to ads in the LA Times, which are viewable as PDF. Updated daily --- there are more ads on weekends than during the week).