[streptomycin]

Agreed, a lot of people don't know their current rights. One major reason is because that information is typically buried in some unintuitive legalese deep in some publisher's website. To work around that problem... this is a very useful database that will allow you to easily check what a journal/publisher allows you to do with your publications: http://www.sherpa.ac.uk/romeo/

Most in my field at least allow you to put postprints (the final version of the paper, but not formatted by the journal's typesetters) online, although there are a few stragglers who don't let you do anything.