I am a founding member of Taxpayers Advocate Inc. and you can browse a full list of the articles I have contributed here. Their Tax Wiki has some great articles and guides to help answer common tax questions.
The CRA have embraced the internet and their website and online services are a great resource for taxpayers. They also hold workshops and online tutorials on several topics and this can be a grear way to learn more about your tax obligations. These links in particular are very helpful:
A fantastic tax resource created by a retired husband and wife in British Columbia. Gives easy to understand information about personal and corporate tax issues.
Created by Professor Benjamin Alarie at the University of Toronto's Law Faculty, this Wiki provides excellent commentary and context for some of the older CRA publications and is expanding its reference centre with a tax dispute portal that can help people access useful information about how to deal with tax problems.
Great resource for charitable organizations and donors brought to you by Mark Blumberg of Blumbergs. The blog and articles consistently give thorough reviews of newly released donation cases and always provide an entertaining perspective on the ongoing tax shelter saga.
Collection of articles and tips for small business owners within Canada with a great focus on simple explanations and practical information.
This great site gives you access to help with Tax Court appeals (including electronic filing of appeals) and the ability to look up the current status of ongoing Court cases and hearing dates.
This site is a portal to information about both the Federal Court and the Federal Court of Appeal and includes up to date information on cases that are before the Courts.
The Ombudsman produces several great guides that review systemic issues within the CRA and can be a great source of information if you are unhappy with how you have been treated by the CRA.
This is where tax law is created and the place to go if you want information on legislative proposals, budgets or even to suggest your own changes for tax reform.