Oceanic abstracts - http://www.csa2.com/ 

Oncogenes and growth factors abstracts - http://www.csa2.com/

Optics education - http://www.opticseducation.com/

Oryzabase, integrated rice science database - 
http://www.shigen.nig.ac.jp/rice/oryzabase/top/top.jsp

Oxford English dictionary - http://www.oed.com

Pacifica Radio/UC Berkeley Social Activism Sound Recording Project - 
http://www.lib.berkeley.edu/MRC/pacificaviet/

PAIS international - http://www.csa.com/

PaperChem - http://www.papervillage.com/  or
http://www.elsevier.com/wps/find/bibliographicdatabasedescription.cws_
home/703037/description#description

Patrologia Latina - http://pld.chadwyck.co.uk/

PhenomicDB - http://www.phenomicdb.de/ 

Philosopher's index - http://www.philinfo.org/ 

ATSDR, Agency for Toxic Sunstances and Disease Registry  - 
http://www.atsdr.cdc.gov/

Physics documents worldwide - http://physnet.uni-oldenburg.de/PhysNet/physdoc.html 

Plant management network - http://www.plantmanagementnetwork.org/

Plant science - http://www.csa.com/

Plunkett research online - 
http://www.plunkettresearch.com/Home/tabid/36/Default.aspx 

Pollution abstracts - http://www.csa.com/

Polymers, a property database - http://www.polymersdatabase.com/

PRIDE, Proteomics identifications database - http://www.ebi.ac.uk/pride/

PrimateLit - http://www.loc.gov/rr/ElectronicResources/
full_description.php?MainID=1372

Project euclid - http://projecteuclid.org/DPubS?Service=
UI&version=1.0&verb=Display&handle=euclid 

Project Muse - http://muse.jhu.edu/

Properties of organic compounds -
http://www.chemguide.co.uk/orgpropsmenu.html

ProQuest Historical Newspapers. The New York times (1851-2003) -
http://www.proquest.com/products_pq/descriptions/pq-hist-news.shtml

PsycARTICLES - http://www.apa.org/psycarticles/

PsycINFO - http://www.csa.com/factsheets/psycinfo-set-c.php

PubChem - http://pubchem.ncbi.nlm.nih.gov/