1. A block that functions as a checkpoint, at least for the player's position. It is initially deactivated. After being pressed, it becomes active and changes it texture, for example. If at least one checkpoint is activated, pressing a certain key on a keyboard instantly teleports the player to the most recently activated checkpoint. The more minimalistic and simple — the better.
2. Abstract simple megalophobic structures (like pyramids) appear randomly far from the world spawn point.
3. Villagers may rarely attack the player at a random moment.
4. A bit off-topic — not sure these are ideas for mods specifically; they’d probably be easier to implement as website services. Still, I think they’d be pretty useful if anyone feels like programming something:
a) Click on an image with an eyedropper tool (like in MS Paint) and get a list of blocks with similar colors.
b) Enter a distance and desired column thickness, and get options for how many spans and columns are possible and what the span lengths would be (for example, for a distance of 23 blocks with 1-block-wide columns you could have 4 spans of 5 blocks separated by 3 columns).
