How can we hide the system tray icons, on the top menu, within OS X?
Those are not mine, but they're not too far off:
Something like Windows 7 has, to selective hide icons into a little window, would be perfect.
The system-related menubar items (Sync, BLuetooth, Wireless, Time Machine, Sound, Keyboard, Time, Battery, etc.) and very few others from 3rd party applications can be removed from the Menu Bar by Drag&Drop while pressing Cmd. Be aware that you e.g. have no way to start a Time Machine backup anywhere else but this menu.
Many applications allow you to configure whether they show menubar icons, for example (in the screenshot) Adium (Preferences, General, uncheck "Show Adium status in menu bar").
Some applications (e.g. Time Sink by Manytricks) leave you a choice between menubar icon or Dock icon: It's your choice which is better.
Yet others require menubar icons, e.g. f.lux, Dropbox (also in the screenshot), or Caffeine; primarily applications without Dock icon. You can only open the application bundle and try to find the icons in there, and replace them with an empty icon. For example, I don't need to see the "Caffeine is running" icon, so I can replace the icon of the coffee cup with coffee in it with an empty image. This will not "remove" the icon from the menu bar, merely make it invisible (you be the judge if this is for you).
You can remove the Spotlight menubar icon by following this hint. You can remove the icon and still have spotlight functionality via an application launcher such as LaunchBar, or any finder window's search box.
The shareware program Bartender can hide most notification area icons.
Some programs have the option within their preferences to 'Show Icon in menu bar'. I turn this off for some of my programs. Likewise, things like battery % has the option of whether or not to show the icon in the menu bar in their section of the system preferences.
I don't know if this will sort everything out, and it does completely remove the ability to get to the icons at all—they would then need to be accessed through the main preferences.