Ruby - 74 characters
a=0
("+ "+ARGF.read).split.each_slice(2){|b|a=a.send(b[0],b[1].to_f)}
p a
Arnaud Le Blanc
- 2.4k
- 14
- 14
a=0
("+ "+ARGF.read).split.each_slice(2){|b|a=a.send(b[0],b[1].to_f)}
p a