Yep, it’s quite a dummy question and the answer is quite simple but many ppl don’t know.
Normally you don’t want to register on all forum’s that you visit but most of them ask you for registration in order to view a post, and the solution (again) is very easy.
Normally most of webmasters ask registration to normal users but they have a “whitelist” rule for bot’s like Google Bot, Yahoo Slurp, MSN bot etc…
So I think you got it, just change your user-agent to some bot and you will be able to view the posts without the annoying registration procedure. So you will bypass the registration forms because normally webmasters let always a door open for Google in order to get up in the web search.
Currently this can be done by adding a firefox plugin, opera currently support only switching to IE or FF but not a bot.