Calling up a cat
Solution 1:
A high-pitched here kitty-kitty is very common.
Solution 2:
(reprise...) I know at least one person who attracts his cat by making the sound we generally write as tsk-tsk or tut-tut. That's the clicking sound made by pressing tip of tongue to roof of mouth, then releasing it sharply to draw air inwards (again, with throat closed). Drifting slightly off-topic, I've long been fascinated by the corresponding "non-vocalised" sound made using the side of the tongue, which has particularly strong associations with horses (i.e. - it means "giddy-up, horse!")