gemspec_snippet.rb

#!/usr/bin/env ruby
def git_config(key)
  value = `git config #{key}`.chomp
  value.empty?? nil : value
end

name = File.basename(ENV['TM_FILENAME'] || 'name').split('.').first
user = git_config('github.user') || ENV['USER'] || ENV['USERNAME'] || 'user'
email = git_config('user.email') || 'you@example.com'
full_name = git_config('user.name') || 'Your Full Name'

puts <<-GEMSPEC
Gem::Specification.new do |gem|
  gem.name    = '${1:#{name}}'
  gem.version = '${2:0.0.1}'
  gem.date    = Date.today.to_s

  # gem.add_dependency 'hpricot', '~> 0.8.2'
  # gem.add_development_dependency 'rspec', '~> 1.2.9'

  gem.summary = "${3:summary}"
  gem.description = "${4:Longer description.}"

  gem.authors  = ['${5:#{full_name}}']
  gem.email    = '${6:#{email}}'
  gem.homepage = 'http://github.com/#{user}/$1'

  gem.rubyforge_project = nil
  gem.has_rdoc = true
  gem.rdoc_options = ['--main', 'README.rdoc', '--charset=UTF-8']
  gem.extra_rdoc_files = ['README.rdoc', 'LICENSE', 'CHANGELOG.rdoc']

  gem.files = Dir['Rakefile', '{bin,lib,man,test,spec}/**/*', 'README*', 'LICENSE*'] & \\`git ls-files -z\\`.split("\\0")
end
GEMSPEC

instructions.md

How to install:

1. Create a new command
2. Paste the ruby code into it
3. Output: "Insert as Snippet"
4. Tab trigger: gemspec
5. Scope: source.ruby

TextMate gemspec snippet.png