Businesses like Ebay, Search and Online Dating are all businesses that are not very good from a technology standpoint. These companies face huge issues because they involve searching and sorting of data. The more data you get into your system the time to search it grows expotentially.
You can visualize this by thinking of an excel spread sheet. If you have a list of a million products all you wanted to find all the ones in blue, you would have to search each row to see if one is blue. As the database gets bigger this requires more and more searching.
This translates into having millions of computers in the case of google, 17,000 for Ebay and a 1000 servers for a company like match.com.
There have been many many companies in the online dating space that have tried to make a business out of free over the years but they have all failed and continue to fail. People forget that as a site grows into the millions of users, the hardware requirements grow expotentially. This results in the Cost of generating a pageview to skyrocket. At the same time the revenue per pageview descreases as people start to use the system for fun and their pageviews per session increase.
Most of the largest dating sites are spending over 1 million a month on hardware and tech staff to keep it running. The only reason my site is still in business and works so well is because i’ve found a way to solve the technical side of the problem.
Social networking for the most part doesn’t make use of ranged searches. A profile lookup by ID or username is like looking up row 1000 in a excel spread sheet. You don’t have to search all the items in the database to figure out what you are looking for, you just want a specific row. Friendster on the other hand did a search of friends of friends. This increased the over all computing power needed to keep the site operational expotentially and killed them off. Myspace on the other hand stripped out everything that would require ranged searches and it became really easy for them to win.
So if you want to make a business that scales really well, try and make one that avoids searching and ranged searches.