Adapters of every kind, from USB-C dongles to world travel plugs.
When I bought the Elevation Dock, it shipped with a 30-pin connector, since the Kickstarter predated Apple's Lightning announcement. Elevation Lab worked hard afterwards on a Lightning adapter, and on 8th November 2012 it finally went into production.
I bought the Apple Lightning to Micro USB Adapter from the Apple Online Store for S$28. It was initially Europe-only, since EU law requires phones sold there to support Micro USB. Last Saturday, Apple made it available worldwide.
I bought the Apple Lightning to 30-pin Adapter from the Apple Online Store for S$42. Ordered on Monday, 8th October 2012, it arrived that same Friday. It isn't in retail stores yet, likely in a week or two.
I bought the Vantec NexStar SATA/IDE to USB 3.0 Adapter from Challenger for S$59.90, or S$53.91 with member's price. As the name suggests, it converts an internal SATA or PATA drive to USB 3.0 for plug-and-play access.
The Apple iPhone Micro USB Adapter is sold only in UK Apple Stores, online and retail, for £8. I bought mine at the Regent Street store while in London for Nokia World 2011. It makes a gift for Apple fans.
I bought the Apple World Travel Adapter Kit before my London flight, at iStudio in Changi Airport Terminal 3, for S$54.21. With a valid boarding pass I skipped the 7% GST, against S$58. The kit works with iPods and iPhones.
I bought a pack of two Taiyo 3-Pin Plug Adapters from Challenger at Funan for S$14.90, or S$13.41 with a 10% member's discount. I like that each of its three 3-pin sockets has an individual switch.
When I got my iPhone 3G in 2008, I hunted everywhere for the universal dock adapter, finding it nowhere on Apple Singapore or at resellers. I only found one a year later in Taiwan at an authorised reseller.