Gouby is good for pennies, and there may well be other specialists for other denominations. Use google to seach on 'coins gouby' or 'coins cooke'. I'd rather not give them free links! But they're not hard to find. Also, the forum here has a few unlisted varieties covered. Most people still refer to Peck, Freeman, Rayner etc. As far as I know, there is no definitive online version. You could also download my book, which lists quite a few, but isn't free: http://www.predecimal.com/books/bookshop.htm