Automatically unarchiving downloaded files

I used a mac a few months back that had this set up, basically if a .rar, .zip, .tar.gz, etc under a certain size was downloaded, OSX would automatically unarchive the file into an identically named directory and delete the archive when done.

It was really convenient and I was wondering if anyone knows how to accomplish this, Google didn't seem to turn up any results for software that will do this, so I'm assuming that automater or some similar system accomplished it.

Any help would be appreciated, thanks

if it's the setting I'm thinking - Since I assume you're referring to Safari downloads -

Goto (this is for Safari 5, it may be in a slightly different place or worded slightly differently in earlier versions):

Safari Menu -> Preferences -> General

Place a check mark in:
Open "safe" files after downloading

aha! I use chrome on my mac, and was using safari on the mac in question, so that would make sense that it's a safari setting. Is there any way to do this without safari? I have to use Chrome / FF for work.

Thanks for clearing up how it worked in the first place though.

In all honesty, I've never used Chrome. I do use FireFox, in theory, there should be an entry in Applications section of Preferences for Gnu Zip and allow you to choose what how you want the file handled. Mine doesn't seem to have that entry so I can't really comment on how to make it work.