I found a very useful article for freelancers during tax time Some comments are just as helpful.
10 Tax Deductions Freelancers Can Make
by Thursday Bram
Tax time can be especially stressful for freelancers: despite paying estimated tax payments throughout the year, it’s rare that a freelancer doesn’t still have to come up with some money for April 15 — or come up with a long enough list of deductions.
There are quite a few deductions available to freelancers that may not seem obvious when you first sit down with all those 1099s and receipts. But as long as you have the right documentation, you can write off plenty of deductions you may never have thought of.
The article is directed mainly to the US freelancers but it also includes links to other countries:
Australian Taxation Office (Business Deductions)
UK Revenue and Customs (Small Business Topics)
Canada Revenue Agency (Small Business Topics)
[Edited at 2009-02-04 08:11 GMT]