Bcrypt is an algorithm which bundles up something which pbkdf2 achieves by iterating other algorithms. They're basically the same, but you should use bcrypt. You shouldn't use both of them, I'm guessing the poster above meant / rather than +. If you want more security, increase your (b|s)crypt work factor.
If for some reason you can't bring the bcrypt code into your project, you can implement pbkdf2 using basically a loop and your stdlib's hash functions.
Scrypt takes the whole concept of placing extra demands on the computer and applies it to the RAM rather than the CPU (perhaps as well as?,) the idea being that RAM is harder to accumulate in obscene quantities than CPU power.
