There are a series of old papers by Bruce Lincoln (now a named chair of History of Religion at the University of Chicago) that makes an argument about the original Indo-European myth. I've heard from other graduate students that he basically "disowns" this early work, but it is very very cool. I don't know how the field has changed since the 1980's or if this work was accepted in Indo-European studies.

That said, in a series of articles in History of Religions ("The Indo-European Myth of Creation", "The Indo-European Cattle Raiding Myth", "Treatment of Hair and Fingernails among the Indo-Europeans", "The Lord of the Dead"), all developed out of his dissertation with Mircea Eliade [there are more in the Journal of Indo-European Studies, but I never read those], Lincoln argues that we can find common--if very thin--themes across Indo-European religion and myth. Certain practices, like disposing carefully of nail and hair clips, especially during certain phases of the moon and if I recall especially through burial, are common (though not universal or unique to Indo-Europeans). In terms of myth, he makes a clearer argument and even attempts to construct "the first Indo-European myth", the creation story (this is very influenced by Eliade who thinks everything begins with cosmogony stories--as you will see, it's also very influenced by Duzemile's theory about a tripartite division of Indo-European Societies into warriors-priests-farmers).

It's been a while since I read Lincoln's pieces closely, but his argument is something like there was a man (*Manu) with a twin (a *Yama), and in most there's a cow, and then the priest sacrifices some combination of the first man/cow to create something important (life, cities). Here's a link to charts showing his data in this reconstruction--first the typologies, and then where he'd got them. In later articles, as he extends to the second myth--that of cattle raiding--he includes more sources, including Irish but I forget which else. Whether this is more suggestive than undeniable proof, and you'll notice some obvious absences (the Greeks, for instance) and that the Romulus and Remus founding of Rome is rather different from the Rig Veda creation of the world.

A more systematic attempt to reconstruct and Indo-European myth--one that pays more attention to words than symbolic elements--Calvert Watkins's How to Kill a Dragon: Aspects of Indo-European Poetics. Instead of looking at plot elements and symbolic names, he looks at the actual texts of these myths and picks out identical poetic formations. I think this has achieved more acclaim than Lincoln's work.

So yes, there are mythic elements that can be picked out by a variety of methods. An archaeologist could likely describe tools, burial styles, and pottery that derive from the I-E heritage. But doing stuff with language besides looking at word/sound/grammar mutations is hard. It takes a lot of comparison and a lot, a lot of work, and is very little rewarded in the academy. "Comparative Religion" in general has taken a hard turn against these sorts of comparison (except with regards to the Hebrew Bible), and indeed, "Comparative Religion" has become a fairly minor part of "Religious Studies". Bruce Lincoln did his work at the tail end of a very different time in religious studies (when Eliade reigned supreme--he's been more or less repudiated except by his direct students). Watkins took a very different, more philological approach (his early work is all in straight I-E linguistics), but you don't see very many philologists around, today. He was also the last of an era, though a very different one. Just the sheer amount of languages that is required to this kind of research makes it much rarer these days. Folkloric studies in general are on the outs, which is really too bad.