A set of Blender Add-ons that can be useful here and there...
File Browser Search is a BlenderAdd-on that allows you to search for files in Blender File Browser (i.e. when linking/appending resources, opening folders, adding images or movies, opening *.blend files, etc.).
Add-on Tools allows you to decided which add-ons should be enabled according to *.blend file and not only by User Preferences.
Group Particles Tools enables a "hidden" functionality of particles systems in Blender which allows better control over particles displayed as objects group.
Mesh Sorting Tools allows you to sort meshes in a more advanced way. It is quite useful when combined with particles or build/explode modifiers.
Animate Render Layers allows you to animate render layers using keyframes. It can be used to speed up renders or replace objects in a scene with for example shattered objects from another layer.