Firefox extensions

Para favoritos o bookmarks
Xmarks Sync
Delicious bookmarks (quicktour)
FEBE
Recover Firefox’s Internal Bookmark Backups
Did you know that Firefox has been backing up your bookmarks all along?  They are in your Firefox profile folder.  First thing you need to do is find your profile folder for Firefox.  Depending on your operating system this may be in a different location.  If you are unsure: 
Where is my Firefox Profile Folder? Once you make it in there you should see a folder named “bookmarkbackups”.  Double-click that folder, and there you have some of your saved bookmarks that you thought you had lost waiting for you to restore them.  If you want more backups to be saved (default is 5) then check out this previous article on the simple about:config tweak you will need to do.
Dropbox
Try syncplaces, it can use a local file folder so you can just point it at your dropbox.
Weave
Right now in that distribution only 3 system type is supported
Linux x86 (32 bit mode)
Winnt x86
and Darwin x86
the other platform the binaries for the crypto library is just not there
It reports it is not compatible with my platform (Linux x86_64-gcc3) and will not install
I think this is accurate, but if you want, you can hack it pretty easily, I just did it to make a frankenstein 0.2.2 for os x ppc. (edit: this hack will make it install. Dunno if it'll work or not)
1. Download the .xpi package from http://people.mozilla.com/~cbeard/weave/dist/
2. make a temporary directory like weave-temp and cd into it
3. unzip the weave-0.2.2.xpi file (it's just a zip file with a funny extension) into that directory, something like unzip ~/Desktop/weave-0.2.2.xpi
4. edit the install.rdf to include your platform (You'll see where and how)
5. zip it all back together with something like zip -r ~/Desktop/my-weave.xpi *
6. from firefox, browse the local filesystem where you made your .xpi file (file:///home/user/Desktop/) give it a click, and install.
That's more or less what I did, and it worked just fine for me.
-Jonathan