This service makes use of a local database of journal titles and ISSN numbers. Simply append a journal name to the URL http://bioguid.info/services/journalsuggest.php?title= and you get back a list of journal names and ISSN numbers that match that title. Try these examples:
Here is a simple autosuggest form that uses this service. Type in a journal name and get a list of suggestions. When you choose one, the form displays the ISSN number of the journal.