The Elink Team has just recently developed a new GBA Expansion kit, the Elink Lite.
It is available for purchase already on some online websites.
The Elink Lite uses normal USB cables for connecting it to your PC for adding ROMs, and is available in 1GB. You must use the included software to do this (not drag 'n drop).
The Elink Lite fits flush into the Nintendo DS Lite.
The Elink Lite will also include two cases (black and white).
Also worth mentioning - the Elink Team recently re-designed their original Elink Flash Kit, and is very similar to the Elink Lite
(more information about that on the Elink website).