OpenOffice.org will have an Firefox's extension-like on their next release, 2.0.4 which is in RC2 version now. The current OpenOffice software can accept some extensions (using UNO and ZIP format), but the upcoming 2.0.4 version will have new extension format, OXT. That format can accommodate extensions written in a variety of programming languages, so you can also build your own extensions if you like and send it to OOo to be included or being put on the repository. Open-source extensions will be housed at a central site, extensions.openoffice.org. People will be able to download the software there. However, because OpenOffice is governed by the Lesser General Public License (LGPL), it's permissible to link proprietary extensions as well.
You might want to read Charles Schultz's blog post also to know more about this.
By the way, there's a feature being requested by Indonesian people in OOo which asked for backup/restore autocorrect in OOo (Bug ID #69491). I think it will be helpfull if this feature will be implemented in 2.0.4, but i kindda doubt it, since it is in RC2 and new features are freezed and perhaps it will deployed in 2.0.5.