Here's a new web ad format, courtesy of Microsoft Advertising dubbed by the online ad industry-standard organization IAB (Interactive Advertising Bureau) as the "Filmstrip" format, it's a new spin on the "half page ad" (300×600). The catch is that it's actually 300×3000 and houses 5 mini-ads in one.
As commenter uberlaff also points out, it's like a panorama from Windows Phone 7, for an ad.
The "Filmstrip" is one of six new formats awarded "Rising Stars Ad Units" for next-generation brand advertising online, chosen from a pool of 36 submissions. These're said to become part of the IAB Standard Ad Units after six months of market testing.