For the US the pretty well known policy bangers are The New Deal and The Interstate Highway System both which are not just socialism but Federal level socialism.
All state run armed forces are by definition socialist in nature. Mercenary armed forces have been used many times to great effect but the backbone of most armed conflicts are the most socialist structure you could create.
Every large modern religion (abrahamic, hindu, buddhist) is socialist in nature and got to the level they are now due to socialist policy.