I really admired Gregg early on in my career. He gave a fantastic talk in Austin, Texas back in about 2007 or 2008 for a Semantic Web Meetup (at a venue called "The Boom Boom Room" funnily enough) back when I was working as the resident search expert and linguist for an SEO consultancy (remember those?). He talked about RDF, OWL, and SPARQL, and some of the iterative ways we could get there on the sites we're building in a way that had me enthusiastic for the web's future. I spoke with him after the conference, and if I remember correctly, he encouraged me to start looking into Lucene after hearing about my job.
Several years later, I'm living in the Bay Area and working for Wikia (now Fandom), acting as their resident Solr expert after taking his advice to heart. Wikia was investing in their structured data initiatives, and ended up bringing Gregg onto exactly the team I was attached to in order to investigate how to apply his area of expertise to our vast store of user-generated, semi-structured data. The opportunity to work with such a talented researcher in a consultative capacity was a tremendous learning experience.
I felt privileged to get to work with someone I had admired early on and made an impact into the trajectory of my career. The takeaway from this is probably that you don't necessarily know whose future your might touch with a presentation or with friendly advice casually offered at a conference or meetup.
Something tells me I'm one of countless cases where Gregg didn't just push the science of structured data and the semantic web forward, but helped to mold expert practitioners through his kindness and enthusiasm for the work. In this way, his legacy will be long-lasting and inestimable.