HEre is a few links:

http://bioportal.bioontology.org/ontologies

http://www.bioontology.org/wiki/index.php/Using_NCBO_Technology_In_Your_Project


Here is an example project that has incorporated BioPortal APIs into annotating google spreadsheets:

http://isatools.wordpress.com/2012/07/13/introducing-ontomaton-ontology-search-tagging-for-google-spreadsheets/


Would something similar be appropriate for choosing a conceptURI for dataset properties?