Take a look at Calibre (for your PC)
- freeware (opensource) and cross-platform
- powerful and configurable e-books database
- custom database fields
- automatic metadata downloading from Amazon, Google Books, ISBN.org and other sources
- compatible with many readers
- web interface (only to view and download books)
- supports many formats (even multiple formats for the same book)
- editor for some formats (epub)
- export database to different formats (CSV, BibTeX and others)
Screenshot from calibre-ebook.org
On your iOS device you could use Marvin Reader and the MarvinXD Calibre plugin:
- add/delete Calibre database books from Marvin
- annotate books
- view reading progress