Linking to individual articles and papers will either be a never-ending project of finding and re-checking thousands, or linking to an unfairly small sample. Therefore, I'll link to a few of the better sources of articles and papers.
If the article, paper or literature view that you’ve found isn’t freely available, then you can always email the author and ask (nicely). Games and education researchers will often oblige in sending a copy to fellow researchers, irrelevant of publisher ownership complications.
Databases and indexes
Google Scholar indexes a lot of material of various formats. Searches return an unordered list, but refining and repeating your search can often return some freely available materials. Try Serious Games or Games in Education, for example.
Slideshare is the largest online source of presentation slide decks. Although the site can be slow and busy with extraneous detail, it contains a lot of relevant presentations. For example, try searching on Games in Education or Games in Learning.
The JISC (Joint Information Systems Committee) have a section of resources concerning virtual worlds and serious games.
Abhijit Kadle has a list of his Top 100 Learning Game Resources, of varying types and media.
Open Access Journals
These are often good places to be published. Many people will read your work, as opposed to comparatively few when it's hidden away in a costly traditional academic journal. Plus, in a fast moving field, your writing gets published relatively quickly.
The journals listed below focus specifically on digital/video games and virtual worlds. However, this being a multi-disciplinary field, many other journals accept the write-up of research in this sector. Try a few searches on the Directory of Open Access Journals to find examples, such as video games AND classroom, or Second Life.
Digital Culture and Education: analysing the impact of digital culture on identity, education, art, society, culture and narrative.
Eludamos (Journal for Computer Game Culture): theoretically and/or empirically dealing with digital games in their manifold appearances and their sociocultural-historical contexts.
Games: strategic interaction, game theory and decision making.
Game Studies: aesthetic, cultural and communicative aspects of computer games.
International Journal of Computer Games Technology: research and development aspects of games technology, covering the whole range of entertainment computing and interactive digital media.
Journal of Virtual Worlds Research: history of virtual worlds, cultural and social theory, quantitative research, qualitative research, virtual ethnographies, pedagogy, education and virtual worlds, development, experimentation, ideas and the intersection of virtual worlds and society.