HNB_.lst is a file created on the SD Card (private/ds/title) when a DSi application/game is copied to the SD Card from Data Manager.
It contains the lower title-ids of the titles copied to the SD Card, each in 32-bit words.
At the end of the file there's an 8 byte section consisting of the language the DSi was in when the list was saved, and a 16bit checksum to prevent data corruption.
Here's a description of the end chunk:
|0||4||Language. 0 = Japanese, 1 = English, 2 = French, 3 = German, 4 = Italian, 5 = Spanish, 6 = Chinese, 7 = Reserved|
|4||4||swiCRC16 of first 0x4B4 bytes (init value = 0xffff).|