NTS:: Metadata sources

More sources of article metadata:

citeulike
This data is useful because it groups related ids for each "view" of a resource (e.g. PMID & DOI for the same article). "
Article linkout data Mapping CiteULike article_ids to resources on the web can be done with the linkout table.
"The current snapshot is available at http://static.citeulike.org/data/linkouts.bz2 Data is available from 2008-02-02 onwards."
"To understand the data in this file, you should refer to "The linkout formatter" section of the plugin developer's guide. This file contains a number of spam links. Although CiteULike filters spam postings, traces of the spam still remain in this table. In time this spam content will eventually be removed. The file is a simple unix ("\n" line endings) text file with pipe ("|") delimiters. Literal pipes within the fields are represented escaped ("\|"). The columns are: 1. Article Id 2. Linkout type 3. ikey_1 4. ckey_1 5. ikey_2 6. ckey_2
NB If an article has n linkouts, then this will result in n rows in the file."

BiodiversityHeritageLibrary
150mb download, but most likely worth it

NZETC (New Zealand Electronic Text Center)
Some solid work, indexed by Index New Zealand, so can use Z39.50 to grab the data from INNZ. I'd like to see what can be done with the TEI-XML too.

NCBI
Worth listing for the version 2 of their wonderful web services.