In May 2011, I wrote about Greplin. Its proposal was appealing: give a search service access to several accounts and find emails, documents and notes through one search box. As people used more services, they spent more time remembering where they had put things.
The problem behind the product
The original list of Gmail, Evernote, Facebook, Twitter, Google Docs and Dropbox describes the situation in 2011. This article is not a current recommendation to connect those accounts to Greplin. The independent idea is finding information without knowing where it was stored. That can matter when a project is scattered across services.
Cross-account search works only if the search service can read or index your data. Some control then moves to another party. Before using such a service, ask which accounts it can access, which permissions it needs, whether it keeps copies and how access can be revoked. A convenient search box may not be the best choice for sensitive material.
Start with your own organisation
Central search can help, but a clear agreement on where documents and conversations belong prevents much searching. Keep decisions and files for a project in one agreed place, use recognisable file names and archive versions you no longer need. Then there is less need to search everywhere at once.
Greplin was a 2011 answer to the growing number of online accounts. The original question remains relevant: how do you find scattered information without losing oversight or control of your data?