I'll also note sports, primarily hockey, as I know it best. In short, the Soviet hockey program revolutionised the way hockey is played. They didn't start playing until 1946, and entered the World Championship for the first time in 1954, where they promptly won gold (granted Canada wasn't able to send its best players, but the point stands). They would win 22 World Championships in 34 years (and medaled every year but one), as well as 7 Olympic gold medals in 9 tournaments (plus the 1992 "Unified Team," which was the Soviet Union in all but name).

The reason for it is that unlike Canada, the USSRs players trained constantly. They literally were kept in barracks for 11 months of the year to train, and while obviously that wouldn't, and doesn't happen in the West/modern world, the methods they used are. Dry land training is huge, as is just basic fundamental skills like emphasis on skating, and teamwork (both severely underappreciated in Canada), as well as a noted lack of physical play. The disparity was made obvious in 1972 when the Summit Series, an 8 game tournament between the best Canadian and Soviet players, was held. Going into the tournament Canadian observers expected a clean 8-game sweep, or at least a comfortable win for the Canadians; it literally took until the final 34 seconds of the last game for Canada to win the series.

All the methods the Soviets employed were eventually adopted by the Canadians (I keep saying Canadians because they were overwhelmingly represented in hockey at this time, but others also followed suit). The results of the Soviet system were clearly evident once their players were allowed to come to North America (post-1991, though a few defected prior); by the mid-1990s some of the top players in the NHL were Russian, only dropping in the past 15 years or so as the older generation retired and the instability of the post-1991 Russia (and rise of the KHL, a Russian-based league) led to a decline in quality from there. But the effects are still seen in the NHL, with many teams emulating the styles pioneered by the Soviet Union.

It did a lot in terms of developing national consciousness for the various ethnic groups within the USSR. By that I don't mean fostering nationalism and all that (which arguably led to conflicts and issues that still plague regions of the FSU today). But their earlier programs saw many minority languages develop their first writing systems, ever (though many of them saw massive changes in the first decades, as in some saw three different scripts used within thirty years; others would change it again post-1991). This obviously had a tremendous effect on literacy and development, especially as the main regions affected (Central Asia and the Caucasus) were some of the poorest and most backward in the Russian Empire.

This was furthered in the union republics (the states that became independent countries) as each was given a full university, academy of sciences, and various other cultural benefits. This further developed the culture and effectively formed states that had never previously existed. While many chided Putin for his comment that the "Kazakhs had never had statehood" prior to the USSR, he is largely correct (I'm aware of the Kazakh Khanate, of which Kazakhstan celebrated the 550th anniversary of its formation last year, but a real Kazakh identity was arguably only fostered in the Soviet Union). That would not have been possible had the USSR not given the Kazakhs their own SSR in 1936. This can be easily said for all five Central Asian republics, Moldova, and to a far lesser extent Azerbaijan and Belarus (Azerbaijan had briefly existed as an independent republic in 1918-1920, and the Azerbaijani identity had only really been created a few years before that; Belarus was also just experiencing a national awakening, but that is a lot more nuanced for here).

Really, the Soviet Union was a great experiment in forming national identity, especially in the early years prior to he 1936 "Stalin" Constitution. The policies were quite liberal, in that they were willing to try bold new experiments, and while it was greatly reigned in post-1936, there is a lasting legacy (it's what my MA thesis is being written on). There were some 100+ nationalities living in the USSR at the time (the numbers fluctuated based on what was considered a national group), and many of them were, for the first time, given the chance to express themselves as a distinct group under the Soviets, if even for a while. The legacy of that is still hugely felt across the FSU.

The Soviet Union pioneered particularly in the realm of scientific and engineering. In 1945 they were a crumbling wreck from the aftermath of the German blitz, in 1957 they'd put the first satellite in space.

The Soviet Union, like other socialist states, also did much (as others have said) to assist fledgling nationalities develop their culture and language. Lenin called the Russian Empire a "prison-house of nations", and Stalin's work "On The National Question" formed the basis of the contemporary Marxist-Leninist and Maoist stances on the right of oppressed peoples to liberation and self-determination.

In the early years, they also focused massive resources on combating illiteracy and improving access to food, clean water, education, etc. Standards of living rose, infant mortality plummeted, etc. Women and ethnic minorities were given equal rights for the first time, and even for a while (pre-Stalin) gays could be open with their sexuality and women could get abortions with no repercussions. (These were later reversed to encourage higher birth rates; scientific consensus was pretty chauvinist at the time.)

And, of course, there's also the massive successes of the Five Year Plans and the Kolkhoz collectivizations of agriculture. We can debate the death tolls to the high heavens, but the fact remains that in the aftermath of those programs, Russia never had a major famine again, and was turned from an agricultural backwater into an industrial superpower in a decade.

Up until the 60's, the USSR was an industrial and economic success given the fact it was lagging Europe and the US terribly prior to 1917.

The irony was that building industries from scratch turned out to be simpler under communism than maintaining them and making them responsive to changing needs.

Source: The Record of Soviet Economic Growth, 1928-1966 (RAND Corporation)