Retailers tend to put certain items on sale at different times of the year. Apartment Therapy has a round-up of what you should buy in June.
Patio furniture often goes on sale in the Summer because most people buy theirs early in the Spring. The prices just get lower as the Summer goes on, so if you're willing to wait, you can expect an even better deal. Check out Crate and Barrel, Pier 1, Target, and World Market for great furniture at a great price.
Indoor furniture also often goes on sale in the summer because retailers are making space for their new fall lines. Again, prices will go down as the summer heads up, but you can start looking around now or finding things to keep your eyes on. Check out West Elm, World Market, and Target for deals on indoor furniture.
Dinnerware is often on sale this time of year just in time for wedding and graduation gifts. Take advantage of the low prices to add to your dish collection or replace broken pieces. Look at Macy's, JC Penney, and Overstock for dish deals.