Note that essentially all of the I2C and SPI eeprom and fram chips on the market have the same interface, and can be used with the same Espruino module.
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
He's talking about external EEPROM or FRAM (depending on how often you have to write it, EEPROM may be fine - you get like 100k rewrites from EEPROM, infinite from FRAM; FRAM also writes instantly byte-by-byte, while EEPROM is written in pages - but the AT24/AT25 modules hide this from you). This is byte addressable storage that works over I2C or SPI
EBay modules (I2C EEPROMs with breakout): http://www.ebay.com/sch/i.html?_nkw=eeprom+at24
Digikey chips: http://www.digikey.com/product-search/en/integrated-circuits-ics/memory/2556980?k=&pkeyword=&pv149=150&pv149=2&pv149=120&pv149=55&pv149=20&FV=1c0002%2C1c0003%2C1c0006%2Cf040003%2Cf040006%2Cf040009%2Cfff40027%2Cfff80434%2C268001d%2C268001f%2C2680042%2C26802e4&mnonly=0&newproducts=0&ColumnSort=0&page=1&stock=1&quantity=0&ptm=0&fid=0&pageSize=25 (eeprom/FRAM/etc SPI and I2C memory chips)
Note that essentially all of the I2C and SPI eeprom and fram chips on the market have the same interface, and can be used with the same Espruino module.