Omnifluids
While playing with the Forestry mod, I noticed that many of its fluids couldn't be placed in the world. The same issue exists with regular milk in vanilla Minecraft. To solve this problem, I created a compact mod that automatically adds blocks for all fluids that don't have them. This happens at the last moment, so don't worry—you'll still be able to get the speed effect by standing in MFR milk.
You can place fluids in the world using a special bucket. If the mod doesn't have its own bucket, you can use the universal bucket from PlayerProxies!
But that's not all! The mod supports special effects for specific fluids. If you have ideas for which fluid and what effect to add (for example, when in contact with the player), be sure to share them, specifying the fluid name and mod.