I tend to use Firefox as the main browser on all my machines for two-and-a-half reasons:
1. The Foxmarks extension keeps all my bookmarks synchronized across all of my machines.
2. The del.icio.us extension makes it just so easy to post bookmarks to pages to my del.icio.us account.
1/2. I can use all the same conventions on both my Windows and Mac machines – that’s only a half because I find myself using my Windows machines less frequently over time and because at least most of the time I do use them I use IE6.
Now it’s down to one-and-a-half reasons because I discovered DeliciousSafari, a plugin for Safari that makes it almost as easy to post as the Firefox extension. It has good features for applying tags too – but it doesn’t have the feature that the ff extension does of copying selected content on the web page you’re bookmarking into the Notes field of the del.icio.us entry. Anyway, it’s worth a try if you’re a Safari user.