Over time we found out that this information deteriorated rapidly with companies going out of business, changing addresses, phone numbers, etc.
Some have suggested (including myself) that the Yellow Pages of your local/regional phone books may be a good solution. Another one that I became aware of recently is the "Edwards Disaster Recovery Directory" which comes in three versions. A hard copy (think the old Sears Catalog size book), CD and then for paying subscribers an on-line version.
Having grown up in the "paper era"there is something about holding a book in my hands that I like. But, it is old fashion--isn't it. The best solution should probably be the on-line one, since it is more likely to be up to date.
Or, once again--how about a Disaster Wiki, where companies can self register and keep their information up to date?