I have a lot of minor projects that follows the semantic versioning standard. Coupled with git flow this makes my life a little easier. Life can always get easier though, so here is a very rudimentary script for retrieving next version from the latest tag in git:

#!/usr/bin/env ruby
inc = ARGV[0]
version = `git describe --tag $(git rev-list --tags --max-count=1)`
v = Hash[[:major, :minor, :patch].zip(version.split('.'))]
case inc
  when 'major'
    v[:major] = v[:major].to_i + 1
    v[:minor] = 0
    v[:patch] = 0
  when 'minor'
    v[:minor] = v[:minor].to_i + 1
    v[:patch] = 0
  when 'patch'
    v[:patch] = v[:patch].to_i + 1
end
puts v.values.join('.')

put it somewhere in you path, and call it something like nextver, and the next time you are doing a release, just run

git flow release start $(nextver minor)

No need for checking what the last release was, it is automagically handled:)