Amicus briefs are never seen by juries. They only guide judges, and in the vast majority of cases, only appellate court judges. They are predominantly filed in the U.S. Supreme Court, a state supreme court, or a U.S. Court of Appeals circuit's panel.
One of the most influential and most famous was the ACLU's amicus brief in the Brown v. Board of Education case, although there are hundreds of notable cases in which amicus briefs are influential, and dozens that are famous. The Anti-Defamation League (an organization devoted to fighting anti-semitism) also filed an influential amicus brief in Brown v. Board of Education.
It is rarely possible to know with certainty how important a brief was (other than through echos of language or reasoning from the brief in the opinion itself), as judicial deliberations are generally strictly confidential.
In a far lower profile case, for example, I once litigated a case in the Colorado Supreme Court in which an amicus brief from the Colorado Bar Association was probably very influential.