A fairly descent/fast go program to enumerate gmail accounts using a glitch by @x0rz as described here
$ go build
$ ./Gmail_Enum
Usage of ./Gmail_Enum:
-d string
Append domain to every address (empty to no append) (default "gmail.com")
-i string
List of accounts to test
-o string
Output file (default: Stdout)
-stdin
Read accounts from stdin
-t int
Number of threads (default 10)