Looking back at arXiv's 25 years (and forward to Open Repositories, next week!), I read through all the old arXiv news on the arXiv.org website, as well as Paul Ginsparg's recent "Preprint Déjà Vu: an FAQ," and put together this timeline (PDF). It It's really interesting to note the start up of additional subject area services at other institutions (and their later consolidation to LANL), the addition of new subject areas, the start up and decommissioning of mirrors, and a lot of other arXiv milestones. It's an idiosyncratic summary, but it was fun to put together. Enjoy.