DS-Xtreme does everything a PSP can
There seems to be a very positive correlation between ease of use and price in the world of homebrew, and the latest all-in-one product is no exception. The DS-Xtreme 2GB is touting itself as a PSP killer, featuring a decent amount of space for homebrew applications, music, and movies. It's an elegant solution, connecting to the PC via standard USB and fitting in the standard DS-cartridge slot with no extra hardware required ... but the damn thing costs $129.99.
If you're very rich looking to break into the homebrew scene, which is actually quite developed on the DS, this is an excellent option, but we do highly recommend a bit of intelligentshopping before making your decision. The DS-X is not yet released, but it's close, so keep an out at their website for the official date and further details.
