I prefer to keep my inventory on Microsoft Word as it gives me the flexibility to have any and all the information I want to keep. I separated my lighthouses into the following groups:

Southeastern
Gulf
International
Northeastern
Great Lakes
West Coast/Pacific
Christmas/Society/GLOWS
Ornaments/Spyglass/Anchor Bays
Speciality

I then list the lighthouses alphabetically in each group and include some or any part of the following information along with a running total for each section of Retail/Paid/Secondary Market Prices:

HL#
Lighthouse Name(highlighted if signed)
State
Limited/Open Edition
Special Instructions
Signed
Variations
Serial Number/Edition Size
Release Date
Retirement Date
Retail Price
Price Paid
Secondary Market Price
Empty Box Location

It may be a little bit too much information but more is better then less.