I've found bookmarks become useless to me and what I do is create simple HTML "control panel" pages and set them as my home page. When my browser opens, I have my control panel with my most common tasks on it, and if some area gets too big (SEO Research, Personal Sites control panels etc, and so on), I can spin that off into a second page that's one click away and also focussed on the tasks I'll be doing next.
I find having it laid out spatially on the page makes it way more useful to me than any bookmarking system I've tried. Knowing where to look if I'm managing my rental or doing SEO research or what have you makes it much more efficient for me.
Then the Control Panel doc is in Dropbox, so it is local to my computer for when I'm offline (I might be playing with a local dev environment and not be online, but still want some bookmarks that are local). I can edit it anywhere and it will propagate to all machines with Dropbox. If you don't need offline access, just put it on a server somewhere and set it as your home page in each browser.
I've tried XMarks, Delicious, the built-browser options and so forth, and this has been way better for me. The people I've turned on to this have pretty much quit using bookmarks. One friend insists on showing me his updated control panel every month or so because he's so enamored with the idea. The only other thing I convinced him to try was LastPass and for him the control panel is a productivity gain similar to Lastpass.
Probably depends a lot on how you use bookmarks, though.