To begin with, I should state that I personally have almost no expertise on foreign coins. However, I do know a thing or two about the Internet, and how to find information in general, so I hope you find this information helpful.
To identify a foreign coin, one should first get all the information describing the coin together that you can. If it has a year on it, any readable inscriptions, detailed descriptions of the pictures and other elements on the obverse and reverse. Determining the country that the coin comes from can be very helpful to identifying and valuing it. This can often be determined from the inscriptions.
If you have access to a scanner or a digital camera, taking a reasonably high resolution picture of the coin can be very helpful. You can put the pictures on the web in various locations for free. For example, www.myfamily.com has free image hosting. Other image hosting companies include Pongo, Twaze, or PixHost. Attaching your photos as email attachments in unsolicited email (that is, without the permission of the person you are sending it to) is bad netiquette. Sending a link/url to a hosted image so that they can see the picture should they want to is much more polite. It also may keep your email from being discarded as Spam.
Once you have all this information, as a first step go to Ebay and browse to the:
Home > All Categories > Coins > Coins: World (click on this last link to go there now)
category. Once there, search for the inscriptions that are on your coin. If you can guess what language the coin's inscriptions are in, think about what languages are spoken in which countries. Of course, if the inscriptions are in Arabic or some other non-Roman language, this can make things more difficult.
If you can find someone selling a coin similar to yours, then you can ask them if they know anything about your coin. You will have to sign up as an Ebay member to send questions to other members.
For a list of countries, with interesting information about each country, visit the CIA world fact book at: http://www.cia.gov/cia/publications/factbook/
For a list of government institutions that are involved in currency, see:For information on various languages spoken, see:
Finally, you can just search for your coin's inscriptions on google, and see what, if anything, comes up:
If your coin is from the Philippines, and says United States, that's a special case. Follow the link to the Philippines page.
If at the end of this, you can still find nothing about your coin, contact me via our feedback form, and I'll try and redirect you to someone who knows more. If your image is hosted, send me the url of the picture.
If you or a friend of yours is an expert in a particular area of foreign coins and would like to answer questions, please let me know that as well so I can redirect questions in a useful direction.