I think I'm pretty typical in that I use a desktop computer in my home office, then grab the laptop on the way out the door. I do have good tools for syncing files and folders between the two, but a glaring problem has always been my browser. I've manually set up my bookmarks toolbar on both machines, and they wind up being just different enough from one another that it is a distraction. I've given up on keeping bookmarks like I used to. Delicious is cool, but not really the right tool for keeping a nice, tidy, hierarchical library of bookmarks.
I don't know what I would do without the awesome Web Developer extension for Firefox.
Suddenly my shortcut key for "Display Element Information" stopped working. This is pretty much the thing I use the most. Long story longer, the conflict is AdBlock Plus (another amazing extension).
In about:config I see an entry to alter the shortcut key for the function in Web Developer, but I do not see an entry to alter the shortcut key for AdBlock Plus. Boo!
The DOM Inspector is a built-in Firefox extension that "can be used to inspect and edit the live DOM of any web document or XUL application." I had never found the DOM Inspector useful by itself, but some components of the (very useful) Web Developer extension rely on it.