SetDirectory["C:/drorbn/AcademicPensieve/2009-01"]

fib[0]=fib[1]=1;
fib[n_Integer] /; n>1 := fib[n-1]+fib[n-2]

Timing[fib[30]]

?fib

fib1[0]=fib1[1]=1;
fib1[n_Integer] /; n>1 := fib1[n] = fib1[n-1]+fib1[n-2]

Timing[fib1[30]]

?fib1

?Save

Save["fib.m", {fib, fib1}]

Import["fib.m", "String"]

Quit and then:

SetDirectory["C:/drorbn/AcademicPensieve/2009-01"]

fib[10]

<< fib.m

fib[20]