Folks have reported reasonably good success with most SDHC (and SDXC?) cards, though I believe there are a few brands/models out there that have been problematic. Will try keep a list here of brands/models that users have had success/difficulties with:
General Advice:
Stick to big-brands (SanDisk / Kingston)
SDHC is recommended
WARNING: some SDXC cards work, others don’t
Aim for 32GB or less
Brand/Model | Experience | User |
|---|---|---|
Onn 128GB | Not working - Gets stuck in mega65-fdisk somewhere within  | traymond |
Kingston 256GB SDXC | Ok - recognised by MEGA65 as 128GB card, but works (discord) | Goetholon |
Team 8GB SDHC (class 4)  | Good (discord) | Lydon |
SanDisk Extreme 32GB SDHC (v30 I)  | Good (discord) | Lydon |
SanDisk Extreme 128GB SDXC (v30 I)  | Good (discord) | Lydon |