Here in Belgium it is not a huge problem disposing of single use batteries for cameras, torches etc.
Many stores have collection points. There is even the added incentive of a free prize draw to win a Toyota Prius hybrid car if you place at least 6 batteries in the envelope and fill in your contact details.

When travelling it can be difficult to difficult to know where to dispose of flat batteries. I do try to use rechargeable batteries but sometimes I end up with the single use variety. I am concerned as they contain all manner of metals that can pollute the environment if not disposed of correctly.
While browsing the Aardvark Travel Bulletin Board tonight I came across this post on disposal points in Spain. I wonder how many countries have similar arrangements?