This is a topic relevant to me too. For me I indeed think there are also technical tools lacking. Because I want to block internet access "smartly" - or at all for the first part. I didn't find a reliable, cross-computer solution that didn't slow down my network speed (like inbuilt router features seem to do).
For IM, I don't use it anymore, I only use skype and mostly am in "busy" mode, even if the "jumping" unread msg/calls counter also makes you crazy. But in this case just remove it from the visible tray part for the time being. Also, ask your coworkers/company to use a dedicated work IM client, like Microsoft Lync! If they don't want Lync (I can understand), just say "x will be our work IM", e.g. Meebo or Pidgin or whatever. Instead of RescueTime I prefer "ManicTime" by the way. Even though I rarely review my times (it's too confusing in ManicTime) and they have some basic issues with logging multiple actions/categories after one another (it's basically impossible, you only log "tags").
How does Outlook get in your way in comparison to GMail? This all depends on your (company and personal) setup! As long as Outlook doesn't crash (it does for me all the time), aren't both similarly distracting? The answer to the question how to limit the time: Decide to limit the time and execute ruthless discipline! It's all a mind game, so sadly you'll have to fix your mind first. ;)
And concerning the e-mails maybe a golden tip: Separate external and internal e-mails! Maybe additionally separate "boss" and "infantry" e-mail. Thus if you get kinda unimportant (or CC:) stuff, mostly all the internal chatter that is distracting and sadly still distributed by e-mail, it will end up getting filtered into a folder you could clean out / process daily after your regular work hours!
Thus you still can get "push e-mail" from all external parties (which you can't filter effectively anyways), while keeping yourself afloat the internal company chatter!
Of course it would help if your superiors would also ask for and implement stricter e-mail and IM rules! Because otherwise people won't change their behavior. As IM is mostly unmonitored, this is a special risk. Here you should just try to be as professional as possible and act accordingly (make this clear) towards your IM chat partner.
Except for that, you could set your smartphone to "flight mode"...while I'm missing a "flight mode" button for my PC ;) as I won't unplug my LAN cable all the time or mess around in the network settings. (And because I'd need a flight mode that allows internet radio, which helps me concentrate on my work!)
So as a last tip, maybe think about which music would make you most concentrated, gather a few internet radio stations with such music, buy yourself a proper noise-isolating (bluetooth) on/over-ear headset and you'll be immediatly much more concentrated. (Assuming you're not a call-center agent. :P)
Also an open-door policy and maximum meeting time rules (esp. for such "open-door meetings"!) might help reduce the stupid e-mail ping pong, as people will just show by.
Last but not least: http://sentenc.es/, e.g.: http://five.sentenc.es/