This page displays the number of entries (articles) in PubMed (Medline) published every year, that conform to search strategy (such as a phrase) you enter.
Directory of Open Access Journals. This service covers free, full text, quality controlled scientific and scholarly journals. We aim to cover all subjects and languages. There are now 4381 journals in the directory.
EndnoteWeb, RefWorks, Connotea, CiteULike, Zotero, Mendeley. Nice summary of the state of the art by Martin Fenner. Conclusion - not much to choose in some ways - personal preference!