Andreas I will without problem pay for use of your database. For me it will always be more interesting than buying the list and having to insert them into a database of my own.
Then the shape you can give to the website will depend of what you want to show. A good example IMHO of a good Internet database with both public (free) and private (not free) access is
www.uboat.net.
The main danger you will be facing will be "data stealing", but I think you can reduce it by limiting the number of requests per day to a reasonable number.