Code:
/*
* Double Jump
*
* Description:
* Allows players to double-jump
* Original idea: NcB_Sav
*
* Convars:
* sm_doublejump_enabled [bool] : Enables or disable double-jumping. Default: 1
* sm_doublejump_boost [amount] : Amount to boost the player. Default: 250
* sm_doublejump_max [jumps] : Maximum number of re-jumps while airborne. Default: 1
*
* Changelog:
* v1.0.1
* Minor code optimization.
* v1.0.0
* Initial release.
*
* Known issues:
* Doesn't register all mouse-wheel triggered +jumps
*
* Todo:
* Employ upcoming OnPlayerRunCmd function to remove excess OnGameFrame-age.
*
* Contact:
* Paegus: paegus(at)gmail(dot)com
* SourceMod: http://www.sourcemod.net
* NcB_Sav: http://forums.alliedmods.net/showthread.php?t=99228
*/
Original Thread
Get an updated version with less OnGameFrame and more updated syntax down
here courtesy of Grey83