You may have come face to face with this problem yourself, and if not, you will soon enough. The Diablo 3 UI (User Interface) only shows 5 buffs at a time, effectively hiding the rest. Now most players will stick below the 5 buff cap, but sometimes you go over it especially in multiplayer when you have "long-term" buffs such as Nephalem Valor or self-buff skills plus buffs from other players.
The solution? Simple! Just add more space for buffs to show. If Blizzard would have allowed mods for Diablo 3 a solution would have been here ages ago, but since they didn't they are going to have to do it themselves.
In a thread started by Perplex about the buff limitations Vaeflare responded with the following:
We agree that it would be great to be able to view more than five of your active buffs, and we’re currently looking into solutions that would ensure players are able to view buffs that are important to them, while also keeping UI clutter to a minimum. Ideally, we’d like to avoid situations where a portion of your screen is overwhelmed by buff icons (for example, just having your buffs stack across the bottom of your bar) and we’re experimenting with different ways to present that information in a format that works well for Diablo III.
While it is great to know that Blizzard acknowledges the problem and is looking for a solution, I don't understand how this can clutter the UI. Diablo 3 isn't WoW; you aren't going to have 20 buffs on at a time. You will at most have 6 or 7, and even then most buffs only last 3 seconds so you don't have to worry about buffs taking over your screen.
The problem now is how long we have to wait for this change to happen. Will it be in patch 1.0.5? Who knows!?