[jodi]

Actually, around here, sellers often write their contracts to buy a house contingent on selling theirs. It's called a "recall" clause - basically a seller of a house will accept an offer with a recall clause that means they agree to accept the buyer's offer and will wait a resonable amount of time for the buyer to sell their current home (usually 30 days, but I have seen longer)...BUT if they get another offer on the property, the buyer then has 48 hours (or whatever you agree on) to remove the recall clause (in essence, agree that they will buy the property even though theirs has not yet sold) or they will lose the sale to the second offer. This happens quite a bit if the buyers cannot afford to carry two mortgages at once - they may lose the house they want if they can't sell theirs fast enough. I have also worked with buyers who could carry two mortgages, but did not want to - they will write in a recall clause to buy a little bit of time to sell their house, but know that they can remove it if they have to (to avoid losing the home). I'm sorry if this does not make sense, but it is hard to explain in e-mail! Definitely get a good real estate attorney! I tell all my clients that their fees are well worth the money (about $350-400 around here - central NY).
A downside: an offer that is contingent on selling a home will nearly always lose out to a comparable offer without a contingency. It definitely weakens the buyers bargaining power. I guess a lot depends on the market in your area too.
I have had clients who received a full-price offer on their home, but only if they closed by a certain date because the buyers were just moving to the area and needed to have a house. They took the offer and rented an apartment for three months until they found a home of their own. Definitely a hassle, but do-able if the price is right!