[choloo]

Try Rock The Vote, old but useful;
*Cvars:
amx_timevote "" // after how many minutes, changelevel will be allowed (Default 5)
amx_howmanypercentage "" // % of players who must vote to make changelevel started (Default 0.3) = 30%
amx_howmanyvotes "" // how many players must vote to make changelevel started (Default 8 )
amx_rocktime "" // after how many seconds vote will ends and server will change the map (Default 10)
amx_directmapchange "" // will show a HUD message with the nextmap name (Default 0)

All players can start the vote with the follow commands:
/rockthevote
rockthevote
rtv