Hang Glider
From Sonic Retro
Hang gliders have appeared only twice within the Sonic the Hedgehog games, seperated by a gulf of many years. The first instance was in 1992's Sonic the Hedgehog 2 (8-bit), and then again in 2006 with Sonic the Hedgehog (2006).
Sonic 2
The central gimmick of Sky High Zone, hang gliding sections were moderately infuriating features of the level's stormy second act. The curved white, orange, and blue gliders were used by Sonic to get from peak to peak. Often difficult to control, players had to run at the stationary glider with as much pace as possible to get sufficient momentum during the flight, and (somewhat counter-intuitively) holding 
prompted a minor boost in height. There were also updrafts throughout the Zone which could be exploited for additional altitude. A hang gliding Sonic featured prominently on many of the game's box and cartridge designs.
Sonic '06
In Sonic '06, the hang glider was available only to Shadow the Hedgehog, along with several other vehicles which the Ultimate Lifeform could hop inside. This heavily armed and rocket powered hang glider included side-mounted missile launchers for blasting aside aerial foes and other obsticles. It appeared in two missions, Kingdom Valley and Crisis City.