I tend to use www.mail2web.com
, and it has worked with all of the providers I have tried. If it lets you connect in the UK (when you are not dialed in through your normal ISP) then I can see no reason why it wouldn't work remotely.
I would have thought the problem you will have in some of your more "obscure" countries with a POP3 phone is getting a GPRS connection with an overseas phone/SIM - but perhaps they are more advanced than I imagine. (I know I have struggled to get GPRS working in some parts of western europe and the US! - I think simply because my SIM card wasn't local).