Below is a downloadable excel file which lists the names of each player in English along with a list of minor leagers, draft picks and trade info. We plan on importing the information onto web pages so if you don't have excel you'll be able to see this information soon.
To view rosters online you can visit this site (it's in English)...
http://www.npb.or.jp/eng/teams/
Official site (in Japanese)...
http://bis.npb.or.jp/teams/rst_s.html