It would be great if there was a column dedicated for profiles (your own and others) displaying always the last profile you have visitied or (if you start up) your own. Looking at profiles (and we do that a lot) is the only action that needs you to move to a whole different level right now and I don't know why.
You could easily fit the column as a 5th column left to the tweet feed. So it would be Profile-TweetFeed(start screen)-mentions-messages-searches etc.
It's alsmost logical - you scroll through your tweetfeed, see an interesting profilelink. click. watch at the profile and then just go right again back to your feed or if you have forgotten something you can take another look at the profile.
Doesn't that sound great? :D