I've read through the topic and now I might post suggestions that already have been posted :

setTimer(function[], interval, repeat)
setTimerEx(function[], interval, repeat, format, values)
resetPlayerWeapons(playerid)
resetPlayerMoney(playerid)
set/givePlayerMoney(playerid, amount)
set/getPlayerWantedLevel(playerid, level) (get without level param)
toggleVehicleLights(vehicleid, lights [0 - off, 1 - on, 2 - main beam (?)])
toggleVehicleEngine(vehicleid, toggle)
OR MAYBE:
setVehicleParams(vehicleid, toggle-lights, toggle-engine, toggle-alarm) instead?
getPlayerWeapon(playerid)
setVehicleLocks(vehicleid, forplayerid, toggle)
setVehicleIndicator(vehicleid, indicator [0 - off, 1 - left, 2 - right])
Add color1 and color2 parameter to createVehicle (maybe respawn delay?)
getVehicleColor(vehicleid)
setVehicleColor(vehicleid, color1, color2)
Maybe a few functions to control the cellphone? (Maybe even SMS/calling? Camera?)
createYellowMarker(x, y, z, size) (should return markerid?)
respawnVehicle(vehicleid)
Menus/GUI's/Dialogs
getVehicleHealth(vehicleid)
getVehicleModel(vehicleid)
Maybe the opportunity to use plugins? (MySQL please)
setPlayerArmour(playerid, amount) (cant find it on the wiki?)
repairVehicle(vehicleid)
setPlayerAnimation(playerid, animationid)
resetPlayerAnimation(playerid)
setPlayerVirtualWorld(playerid, worldid)
togglePlayerRagdoll(playerid, toggle) (maybe for custom death scripts?)
Question By checking player models I found out that each pedestrian got several clothes? Like coat, suit, t-shirt and so on. Will they change clothes each time you set a model? Because that would be freaking awesome!