We all know the item selection of Minecraft is limited. So, I came up with the idea of adding some new items (foods, blocks, useless-quest-items, etc) possibly even taking the idea of cooking+crafting a step further (craft together apples, egg, milk and bread(?) to make pie-dough, then cook it to make pie)
However, just like my new-mobs idea, I got to wondering if this was all controlled server-side or client-side... if it's client-side, there is no real way to just "patch in" new items (without patching server AND client)
I know that you can add new blocks to the single player version of MineCraft, there are several mods that do so. However, unlike simple texture mods, you need to fiddle with the internals of the game in order to introduce new blocks. I know this is possible to do without modifying the game .jar file, which seems to be a major concern for Notch and mods.
I have not, however, seen a multiplayer mod that adds new blocks that aren't created from recipes. You can create new recipes from existing blocks, but no mods exist that add new dirt, metal and rock. I don't know if this is impossible, or if folks just haven't bothered (due likely to the amount of obfuscation in Notch's code), or if folks just haven't thought it necessary or desirable.
I'm wondering about not so much adding new blocks but just copying existing ones, modifying their attributes, and recoloring them. Such as Diamonds/ore/blocks recolored red for Rubies (and subsequently a new set of armor/weapons that are ruby/red) ... As much as I'd like to add new items alltogether I can live with just duplicating and editing existing ones...