I think the guys in alsiarat.com did it manualy.
It's not search by cities but by keywords and the keywords happened to be cities here.
Look at he target url, for ex:
http://www.alsiarat.com/?s=Ajman
For this you need a basic javascript code to implement the jumb box.
Something like this:
<form name="jump1">
<select name="myjumpbox"
OnChange="location.href=jump1.myjumpbox.options[selectedIndex].value">
<option value="http://www.yourdomain.com/?s=city1">city1
<option value="http://www.yourdomain.com/?s=city1">city2
<option value="http://www.yourdomain.com/?s=city3">city3
</select>
</form>
- For all cities, the guys there linked it with the home page
- his feature can be coded dynamically to collect all the cities used in the submited ads, so if anyone has a clue how to do these mods, it would be great to show upwith some ideas.
I hope this can help.
Cheers