Download files like mega.co.nz

Mega uses several different methods to do this: (as of 27 Nov 2013)

1. Filesystem API (Chrome/Firefox Extension polyfill)
2. Adobe Flash SWF Filewriter (old browsers fallback)
3. BlobBuilder (IE10/IE11)
4. MEGA Firefox Extension (deprecated)
5. Arraybuffer/Blob (in memory) + a[download] (for browsers that support a[download])
6. MediaSource (experimental streaming solution)
7. Blob stored in IndexedDB storage + a[download] (Firefox 20+, improvement over the in-memory Blob method)

(source: https://eu.static.mega.co.nz/js/download_6.js)