Cell phones are going on sale during the long Memorial Day weekend. Two of the largest online cell phone discounters are having head to head Memorial Day sales.

Amazon and WireFly (and Let’s Talk, but they have not announced any special Memorial Day based sale) discount their phones from what consumers would pay by going straight to the carrier. All three carry phones and plans from Sprint, Verizon, T-Mobile and Nextel. Only Amazon has deals on AT&T phones and plans.

Taking a look at what Amazon and WireFly are offering, in addition to their regular discounts:

Amazon – Amazon Wireless has about 20 4G smartphones in it’s Memorial Day sale. Some examples include the Samsung DROID Charge for $179.99, and the HTC ThunderBolt for $129.99 on the Verizon network. The Samsung Infuse for $129.99 and the HTC Inspire for a penny, on AT&T. The Google Nexus S on Sprint for $49.99. On T-Mobile is the Sidekick for $49.99, and the G2x for $119.99. Amazon is also giving students a $10 Amazon Appstore credit with purchase of an Xperia Play from not to 6/4/11, and a $25 Amazon gift card with the purchase of a Windows phone, good until 5/30.

WireFly – WireFly is also focusing it’s Memorial Day sale on Android smartphones. They are offering  the Droid X on Verizon, the Sanyo Zio on Sprint, and the Cliq XT on T-Mobile, all for free with a contract. The new LG Revolution is on sale for $199.99 on Verizon. And the Sony Ericsson Xperia Play on sale for $99.99.

Of course, both discounters require a new two year carrier contract to get the phones at these prices.