Sum of integers in string, separated by non-numericals such as 'a' and 'Y'
Ruby 1.9, 21 characters

eval a.scan(/\d+/)*?+


To print the solution to stdout, 2 additional characters are required:

p eval a.scan(/\d+/)*?+


And to read from stdin instead of using a predefined variable, another 3 characters have to be used:

p eval gets.scan(/\d+/)*?+


For Ruby 1.8, replace ?+ with "+" to get a working solution in 22 characters.