Meta Search - Search your Desktop, Google Drive, Dropbox, Gmail, Evernote.
WorldBrain (Re)search-Engine - Full-Text Search your Browsing History & Bookmarks
Findo - Your smart search 🔍 assistant across personal cloud ☁️
Microsoft Web Activities - Microsoft's new extension bringing timeline to Chrome
FYI - Find your documents, like magic 🔮
Better History - Your Chrome Browsing history. Better.