Here you can find examples of real sites using Relevanssi to power the search.
Hey Epiphora (NSFW) – A sex toy review site uses Relevanssi to provide relevant search results.
Media Burn – Independent video archive uses Relevanssi Premium with custom weights and results ordering.
WhiskyCast – Whisky podcast. Relevanssi-powered search, with special searches for tasting notes and events.
Li-An blog – Comics author Li-An (also the French translator of Relevanssi).
Kirjavinkit – The search matches user profiles and taxonomy terms as well as posts and pages.
Lautapeliopas – The search results show game review matches first and everything else after that.