Charity Work

Hey Guys,

To all business gurus:

I'm really interested in doing a bit of charity work over the summer, to kill some time, flesh out my portfolio, and to do something constructive for a good cause. However I'm wondering if there are any points to look out for when working for non-profit organisations, i.e. do they have an identification number which can be checked to prove that they are really a non-profit organisation, or a registered charity?

Also I was thinking of sending letters and cold-emails to them, offering my services for free of charge as well as hosting for the website. Would this be the best method of contact to 'touch-base' with them?

Thanks in advance