Nokia has an offer open for those who have purchased a Lumia 820 through O2 UK. Free wireless charging shells are available to enable wireless charging when used with supported docks and stations. The offer is available until January 18th, 2013. Unfortunately this offer is restricted to O2 and only covers specific dates.
Only one charging shell is available per qualifying purchase, which has to be made through O2 with two eligible dates present in the redemption form - November 7th and 8th. If the offer is limited to the two days it's a slight let down, but a free wireless charging shell is a worthy addition to the Lumia 820, especially if you're planning to purchase a charging plate or already have one from the carrier.
O2 is currently (and has already been) offering a free charging plate with all Lumia 820 purchases, and availability starts at £36/mo with no upfront fee or £26 with a £299 initial fee.
Be sure to head on over to Nokia's free charging shell redemption website, where a form can be filled in with personal details, IMEI number and more. Also, it's worth checking out the terms and conditions before continuing through the offer.