I maintain ConceptNet [1]. It's a large-ish, messy semantic graph linking together crowd-sourced knowledge (from Open Mind Common Sense, Wiktionary, some Games

I maintain ConceptNet [1]. It's a large-ish, messy semantic graph linking together crowd-sourced knowledge (from Open Mind Common Sense, Wiktionary, some Games with a Purpose, etc.) with expert-created resources (WordNet, OpenCyc, etc.) [1] http://conceptnet5.media.mit.edu http://conceptnet5.media.mit.edu It's turned out to be a good input for machine learning about semantics, which has changed the goals of its representation a bit -- not only do I need to be able to load in data easily, I also need to be able to iterate over all of it. But some graph operations would be nice to have, too. Many technical people I describe the project to immediately ask me what graph database I'm using, both before and after the ill-fated semester of grad school where I actually tried to use graph databases. The answer to what I use now is: a bit of SQLite and some flat files. No need for HDFS, it still fits easily on a hard disk.