In my experience of holidaying in Europe & North Africa, tips for chamber maids etc are given at the end of the holiday/stay and more often than not given directly by oneself to the chamber maid, rather than being left anywhere.
Money left on a table would almost certainly not be seen as tips for cleaning your room, as indicated in Karlson's comments.
(Hotel staff wouldn't dare touch money left on a table simply for implications of theft, their job is too precious to risk, beside it simply not the done thing (at least in Europe, North Africa & I'm certain most parts of the world). To be perfectly honest with you I have never actually heard of people leaving loose change, be it coins/ notes on a table indicating it is for chamber maids/cleaning staff).
In terms of leaving a tip, you should definitely give it (unless you have grave reservations not to), they definitely expect it, even if they don't directly ask or hint at it. Wages are generally very low.
The same would apply when tipping a so called "Bell Boy" (hotel porter)