Electronic Research Announcements of the AMS is perhaps one such journal. But why not publish in Comptes Rendus? It is well known the world over and has many gems (with complete proofs). For example, Gabber's proof of a deep finiteness result in etale cohomology is in O. Gabber , Sur la torsion dans la cohomologie l-adique d'une variété. C. R. Acad. Sci. Paris 297 (1983), pp. 179–182.