One of the things I like most about GMail is the way it groups messages together into conversation threads, including the messages that are from me. Now that I'm using it, I can't believe I've put up with conversations being split across Inbox and Sent for so long in other email tools.
I use Outlook at work (I won't go into why here - that's a rant for another day...) and wondered if I could achieve something similar by setting up rules to copy incoming and outgoing messages into a single folder. I set it up, naming the folder "Onebox", and it worked - with the list of messages grouped by conversation, each thread contained my messages as well as those of others, keeping everything nicely in context.
I'd only been using it for five minutes when I realised I didn't need the new folder and the rules - I could simply make a search folder, including messages from the Inbox or the Sent folder, which has just the same effect, but keeps a separate Inbox and Sent too, just in case there's a use for it.
I've also added an automatic formatting rule for the Onebox search folder, to make my name appear in a light grey text on my messages in conversations, as a more immediate way to see the pattern of to and fro in the list of messages.
So...one Outlook problem down, only five gazillion or so to go...