The India Code is posted by the Ministry of Law, Justice, and Company Affairs. Decisions of the Supreme Court of India are available on Lexis (INDIA;INDCAS). Business laws concerning corporations, partnerships, antitrust, securities, etc., are posted on the Ministry of Corporate Affairs' Acts & Rules page, as well as Circulars, Notifications and Guidelines. The Ministry's Limited Liability Partnership site posts Acts, Bills, Rules and other legal materials concerning LLPs. Income tax Acts, Rules, Circulars and Notifications are posted by the Department of Revenue. India Kanoon provides a free search engine limited to Indian primary law sources.
Halsbury's Laws of India provides a detailed discussion of India's laws; check Worldcat to find libraries holding Halsbury's. The treatise Digest of Commercial Laws of The World , available through Westlaw, includes a chapter on India. You may also want to check out Tax Management Portfolio No. 966-4th: Business Operations in India. A good news source is the newspaper India Abroad.
For links to more primary Indian law and law-related web sites, visit the India Legal Information Institute and the Guide to Legal Resources: India. For more information about Indian law and legal resources, see the Guide to Indian Laws by V. Ramakrishnan, A Guide to India's Legal Research and Legal System by Dr. Rakesh Kumar Srivastava, the Legal Research Guide: India by the Library of Congress and the "Foreign Laws" entry in this Guide.
Business Information: ET Now provides free stock quotes, financials, and other basic company information on companies in the "ET 500."
The Ministry of Corporate Affairs' MCA21 site lets you Check a Company or LLP Name to see if it is registered. The Find A Company search includes lists of each company's filings. If you register and log in from the home page, you should be able to purchase the company's filings through the Find A Company search.
The Ministry of Corporate Affairs provides a similar site for Limited Liability Partnerships that lets you look up an LLP Profile or Check LLP Name Availability.
Reports on Indian companies can be purchased from SkyMinder.
Intellectual Property: The EPO's India page provides information about Indian patents. See also Patents - Foreign, Trademarks and/or Copyrights.