Python 3.x

Well, I'm not going to win any prizes for the shortest output code but maybe for the program to generate the code...

x=input();o=''
for i in x:
 a=ord(i)
 o+="+"*a+".[-]"
print(o)

x=input();o=''
for i in x:
 a=ord(i)
 o+="+"*a+".[-]"
print(o)

'Hello, World!\n':

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++.[-]++++
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+++++++++++++++++.[-]+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+++++++++++++++++++++++++++++++++++++++++++++++++.[-]+++++++++++++++++++++++++++
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+.[-]+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++++++++.[-]++++++++++++++++++++++++++++++++++++++++
++++.[-]++++++++++++++++++++++++++++++++.[-]++++++++++++++++++++++++++++++++++++
+++++++++++++++++++++++++++++++++++++++++++++++++++.[-]+++++++++++++++++++++++++
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
++++++.[-]++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++++++++++++++++.[-]++++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++.[-]
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
++++++++++++++++++++.[-]+++++++++++++++++++++++++++++++++.[-]++++++++++.[-]