Selecting a sub-conversation out of a long, multi-person conversation.
Do you ever have a long, multi-person conversation, and you want to concentrate on a particular sub-conversation with one person? For example, let's say you emailed three of your buddies Ada, Bob, and Cat, with the subject "Job okay?" and asked them all "How's it going at your job?". They all replied back and now you've gotten into three separate sub-conversations all within the same Gmail conversation. There is an easy way to concentrate on your sub-conversation with, say, Ada. Simply do the following search (without the square brackets):
[ subject:"job okay" (from:ada OR to:ada) ]
(Note that the "OR" must be all caps to be recognized as a special operator.) Then when you click on the conversation, it will open up with only the matching messages expanded! =)
Here's more detail than you probably want to know: The "to:" operator finds stuff in the to/cc/bcc fields. If you also cc-ed or bcc-ed Ada in other messages that you don't want to match the search (e.g. your messages to Bob and Cat), then do the search:
[ subject:"job okay" (from:ada OR (to:ada -cc:ada -bcc:ada)) ]
The "-cc:ada" and "-bcc:ada" terms eliminate the possibility of matching on messages cc-ed or bcc-ed to Ada.