Stable download URLs One big problem that I'm regularly facing is that URLs for downloading Bioinformatics data (e.g., RefSeq releases or NCBI genome releases) disappear.

Does anyone have any good solution for this?
The Persistent uniform resource locator or PURL is one such solution, these are designed to be a bit more robust than permalinks in so much as they are supposed to survive the change of domain name.  The bio ontology community already use them http://purl.bioontology.org/docs/index.html