If you don't attend school, you can see if a school provides access to their library for outside third parties.
I found out that I can do this for Princeton University for $300 a year.
I am having trouble deciding what I would focus my research on when I go for my Ph D. As AJed mentioned, ACM digital library and IEEE xplorer would be near the top of list.
Additionally Goggling with advanced search for the name of the reference with the option to search for PDF or PS increases the change of a hit.
Ontologies of research areas are important tools for characterising, exploring and analysing the research landscape.
We recently released the Computer Science Ontology (CSO), a large-scale, automatically generated ontology of research areas, which includes about 26K topics and 226K semantic relationships.
Sometimes limiting the search to as a search term because many researchers write survey papers so that someone new to the subject has an informed person guiding the way.
I also like to hit Cit Seer X, World Cat and Google Scholar Don't forget to look at the patents in Google Scholar, I don't usually but every now and then companies have to give out something good they may not publish anywhere else.
Conference series might be from ACM, IEEE, or Springer LNCS.
Also, Google is a good help, but single papers in the arxiv do not tell about the "status" of the research.