Computational logic systems, such as theorem provers and model checkers, produce evidence of a successful proof in an assortment of (often ad hoc) formats. Unfortunately, the evidence generated by one prover is seldom readable by another prover or even by a future version of itself. As a result, provers seldom trust and use proofs from other provers. This situation is made all the more regrettable given that logic and (formal) proof are certainly candidates for universally accepted standards. I will overview some recent work on designing a trustworthy proof checker that is able to check a range of proof structures (eg, natural deduction, resolution refutations, and proof nets) in classical, intuitionistic, and linear logics. I will also describe various future directions for this effort, including building marketplaces and libraries for proofs and developing ways to check and use partial proofs and counterexamples.