Here are a few useful links for finding out more about specific tax issues.
HM Revenue and Customs
HMRC Online Payment Service
You can now pay your tax bill by debit or credit card. Please note for credit cards a non-refundable transaction fee of 1.25% is added to the charge.
Taxation Web
Online tax community
Business Rates Info
Tax Indicator Document Archive
Useful tax documents and aids
Offshore Companies
Formations and lots of advice
Tax Aid
UK charity providing free tax advice to people who cannot afford to pay a professional advisor
Professional Contractors Group
Lots of IR35 assistance