Make your mobs bleed a little
BleedingMobs creates a blood effect, when you hit animals, monsters and other players. It generates blood particles using wool and redstone drops, that disappear after a short time and stain the floor with colored wool blocks. All particles can't be picked up and the wool blocks on the floor can't be broken. This plugin is highly customizable in the config.yml. If you need more options, just add a comment or create a ticket.
You should watch the videos to see the effects in action.
The idea for this project came after watching Yogscast: "Shadow of Israphel" Part 25 and 29.
Permissions You need the permission bleedingmobs.admin (default: op) to use the /bleedingmobs command. You need the permission bleedingmobs.bloodstrike (default: true), if you enable permission-only in config. If you enable the permission bleedingmobs.noblood (default: false), you will not bleed when hurt.
Statistics Since Version 3.4 this plugin sends statistics about the usage to the server http://mcstats.org/. You can disable it using the command /bleedingmobs disable-metrics