In genealogy it helps to be a ‘completist’. I always like to have a complete list of all records, sources or websites available, so that when I search I know I am not missing anything. As more and more goes online it becomes increasingly difficult to know precisely where to start a search. Often we need a complete list of websites that deal with, or hold information about one subject, so that we can make that our starting point. Step forward Wikipedia, not normally the best place to start your research but now providing links to a long list of online newspaper collections, indexes and individual newspapers. The list is international, divided by country and, very usefully, shows what is behind a paywall and what is free.
http://en.wikipedia.org/wiki/Wikipedia:List_of_online_newspaper_archives
It is probably not 100% complete, but is an excellent jumping off point for any researcher, particularly those looking for online newspapers from the USA and other places outside the UK.