The rules are different everywhere.
Personally; buy a computer game, write a review, post it on a blog, claim computer game, play computer game for 120 hours, shower, repeat.
I claim lots of stuff. PC's (depreciation), a business share of mortgage interest, electricity, heating, water, rates (i work from home), credit card interest, hosting, domain names, scripts I've purchased, bank fees, car use (to bank, post office etc), ppc expenses, subscriptions to webmaster sites, newsgroup access, telephone... the list goes on...
/ worked last tax season for major tax people
Oh, make sure you put adsense or something on that blog. As long as the expense was incurred to generate some income (intent), you should be alright. The tax man should have no problem with you claiming a $100 game and earning $6 in revenue.
// don't work for major tax people any more
/// this is not advice.
//// slashies!
///// you should consider your own persona... fuck it. that's enough. do your own homework.