Since Slimes are some peoples favorite mob, and the item they drop on death is useless, I came up with an idea for it.
Table of Contents
 = Glue
Slime Balls( ) are drops from Slimes.
Glue( ) is made from Slime Balls.
  
  --> x2
  
Glue should resemble green gunpowder.
Glue is used to make Sticky Redstone( ).
  --> x1
  
Sticky Redstone should look like redstone with a slight green tint.
Sticky Redstone takes slightly longer to pick up, but can be placed on walls and ceilings.
You could also used Glue to fix tools.
Lets say your Diamond Pick is almost broken.
You have glue, so you do this:
  -->
  
And the diamond tool would gain back 2%.
Different materials should gain back different amounts
Wood = 10%
Stone = 7%
Iron = 4%
Diamond = 2%
Gold = 50%
High amount for gold to give gold tools some purpose.
[Thank vork for the fixing items idea]
Glue could also make Sticky Sand/Gravel.
= Sticky Sand/Gravel
  -->
  
The sand can be sand or gravel.
If Sticky Sand/Gravel is put down, it won't fall.
If Sticky Sand comes in contact with water, it will fall.
Sticky Sand/Gravel will both fall when in contact with Lava.
[Thank will1b for Sticky Sand/Gravel idea]
This would make for some new traps.
They are made like this:
  
  -->
The Log can be ANY block.
When made, it looks like whatever block you put at the bottom, but with a VERY slight green tint.
When stepped on, it freezes whatever stood on it.
If they move around a lot, they get off, the block becomes a normal block, and whatever got off moves 25% slower for about 10 seconds.
Slimes, when walking, have a small chance of dropping Slime( )
Slime must first be put on the work bench to make Slime Balls.