If you are using Safari, you should also get the SafariPlus extension (
http://web.mac.com/jrc/SafariPlus), which gives Safari two key new capabilities:
1/ It can clean out cookies and other temporary data each time it exits. This is a nicely done piece, since it lets you select cookies that you can mark as permanent, and it will only delete the rest. So, you can keep all the cookies you actually want kept, and have it auto delete the rest on each exit. Nice.
2/ It provides grouping of cookies. I am sure we have all been a website that drops 20 cookies on the machine. When you go to clean up your cookies in Safari later, you have to select them all and delete them each manually, or in groups when you can. With SafariPlus installed, you get grouped cookies. All of the cookies from any one website are together in a nested list - you can just delete the top level of the nested list and they all go. This is nice. Also, it makes taking a quick look at what cookies are on your machine a lot easier, since you just see the nested list. Instead of seeing 100 cookies, perhaps associated with 10 site, you just see 10 nested sets - MUCH easier to comprehend.
If all of this sounds familiar, it should. Firefox has had the above two behaviors for some time.