EVE-Central.com has several APIs, feeds, and dumps for querying contributed market orders. Note that this is not live and 100% accurate data, as it is provided by users using a market exporter utility.
Included in the data is:
- Currently active market orders query (XML via HTTP GET)
- SMTP based feeds for all market orders contributed (CSV via SMTP)
- Aggregate information queries used by several utility, such as EveMon (XML via HTTP GET)
- Nightly database dumps (gziped CSV via HTTP)