NemakiWare is designed for this.
- Upload your files, use them, organize them as you like.
- Search by filename or by content (full-text search). For instance, if a PDF (or Word file) contains "ECM", then you will find it by typing "ECM" in the search box.
- You can create groups, and set folders/files to only be viewable (or modifiable) by certain groups.
- Modify documents when you want.
- All of this via the web interface. You may also choose to use NemakiWare's desktop sync client (similar to a Dropbox client).
You can install NemakiWare on your own or rented server (not as easy as ownCloud: you need to install Java and CouchDB first), but a cloud service is also available (at a cost).
Bonus: It is open source.
Disclaimer: I work at the company that makes NemakiWare.