Looking into DS homebrew...

[The_Amaster]

but I'm not sure what flash-SD chip thingy to buy. I'm looking between M3DS (http://www.gameyeeeah.com/m3-ds-real-card-rumble-ram-pack-p-805.html) and R4DS (http://www.gameyeeeah.com/r4-ds-r4ds-kingston-micro-sd-tf-2g-memory-card-p-1016.html).

Is either one significantly better than the other? For that matter, what kind of software am I going to need to run the apps I get?

[Breaker]

M3DS real. it's updated regularly and supported more than any other device. i use it myself and swear by it. you can grab the most up to date firmware from here (http://gbatemp.net/index.php?dlcategory=70).

[MottZilla]

I second M3. I have the M3 Mini-SD slot-b device which is still supported by them to this day. They've done a good job. Slot-b devices in my opinion are nicer since you get GBA support.

[The_Amaster]

Okay, cool. That strong of a recommendation from two people sounds good by me.