ZuZu! in Central had pretty good middle-eastern-ish food. Cafe Barada on Mass. Ave nearish Porter has yummy middle eastern food, but it's quite a ways from Harvard Square at that point.

i've heard good things about Centro, somewhat pricey Italian in Central Square, though i haven't been there myself.

Zagat's suggests Skewers in Harvard Square (Mt. Auburn/JFK), as a decent cheap middle-eastern place; i haven't been there, but it might be worth trying.