If you stay at the Bellagio for at least 2 night and use code BELOLV, you can pay as little as $90 a night! The restrictions and rules are simple, the longer in advance you book, the more you save: if you book 60 days prior to check-in you get 25% off; if you book 31-60 days prior to check-in you get 20% off; and if you book up to 30 days prior to check-in you receive a 15% discount. This promotion only runs from April 22, 2009 - September 10, 2009 and can not be combined with group or other discounts.
If you want to see show while you're there, this same code applies to discounts at both the Cirque du Soleil shows Love and "O" for 25-40% off certain dates and seats. I checked some dates in late August for the ""O" show and I could still get front row wet seat tickets, so book now if you want a great deal on both your stay and a show.
It may get hot in the summer in Vegas, but some of the coolest deals are found at the oasis of water shows in the dessert.