I have the Swing-Grips from Gamestop (don't bother to check their site, it isn't listed there) with my DSlite and it has an area under the DS for 3 DS carts and a stylus. You could use one of the spaces for the DS cart to hold two microSD or miniSD cards in their standard SD converter (like I do) or all three spaces to hold 6 of the suckers. If you don't need the convertor, you coudl store a whole bunch of them in there.
I have pics of my DSlite in the Swing-Grips, but I don't have a shot of the compartments underneath........
Hang on.....let me take a quick pic of the compartments under the DS.....I'll post the older pics and the new one that shows the inside area....
....here we go:
The slightly yellowed area in the third pic is a rubberized sort of stuff for comfort and added protection. I have both my miniSD and microSD cards in their converter in that first slot.
The grips might be kinda ugly to some people, especially if you don't have a white DSlite, but they are a godsend for people that get hand cramps while playing the DSlite. No ports on the DS are blocked.
They're about $10 at Gamesop. They are made by Naki.