I've been trying to follow the new update (1.5) closely through the snapshots. I've also figured out pretty much all of the uses for them, which is a lot. One thing that annoyed me was when minecraft adventure mode was updated so you could break blocks with the tools they require. So with my knowledge of the commands I believe I have a few suggestions for some new gamerules and commands.
Firstly, there should be a gamerule for breaking blocks. You would not be able to break any blocks (or entities) even with the proper tools. You would also be able to edit which block you could and couldn't break. The usefulness for this would be something like a mining system in an adventure map (like in Skyrim). Combined with adventure mode you could only mine ores with a pic. Also with a few MC edit filters you could make the ores regenerate.
Second, a crafting limiter, Just like the previous one you could choose exactly what recipes you want to allow and which ones you cant use.
Third, a placing limiter, again just like the previous two but for placing blocks.
There should also be a saveinfo command to remember a players name/level/team etc. and save it to a variable you would decide. The command might look like /saveinfo @p [type] [name]. You could then use that variable elsewhere in a command like /getinfo [name] [output_if_true/restore] where output_if_true would output a redstone signal through a comparator if the info matches, and where restore would put those saved variables on somone again.
Those are the ones I've come up with but if you have any more suggestions for commands or gamerules I'd love to see them.
P.S. I apologize for any spelling mistakes, i'm not the best speller
New gamerules are not even effective, just annoying. I want Mojang to leave traditional things in Minecraft alone!
As of you, how about you say why they are annoying? Your opinion is irrelevent unless you support it with facts and/or reasons. Gamerules dont effect everyday play, so why should they not add in more? You can play on survival and not worry about them. If Mojang "left the traditional things in Minecraft along" then we wouldn't have TNT carts in the next update. TNT carts man, TNT CARTS!!!