CF and SD card install
For the last few years I've had laptops running on CF cards and SD cards. It is a fantastic idea, especially for older IDE based laptops. (Try finding a new 2.5" IDE drive for less than $50. CF adapter + card = $30.) Here's a quick rundown of installing and running.
Have a cdrom drive? Make two partitions. The first about should be 100-200 Mb, the emergency partition. More on that later. The second takes up the rest of the drive. Do not make a swap.
No cd drive? dd the usb .img file to the card. Open the drive in a partition editor. You'll see one 180Mb partition. Boot this to install Arch. (Later it can be used for rescue purposes.) Add a second partition taking up the rest of the space. Same thing, no swap partition.
Format the primary partition as ext2.
Don't worry about no swap. You know how a normal computer slows WAY down when it starts hitting the swap? You'll feel the same effect even without swap. When memory gets low, shared libraries are automatically unloaded to free up more space. But your apps still need to use these libs, so they get read from disk (slow!). You'll feel the slowdown long before hitting an OOM error.
Follow the Beginners' Guide to install. When it comes time to edit Template:Filename, you should use the following. Add one line to move Template:Filename into ram, use UUID to use persistent naming and change your primary mountpoint to "noatime,nodiratime" to reduce wear:
tmpfs /tmp tmpfs nosuid,nodev 0 0 UUID=... / ext2 defaults,noatime,nodiratime 0 1
You may also need to add usb to Template:Filename in order to boot correctly from a card on an usb card reader. If you need input from usb devices (i.E. password for dm-crypt) you need usbinput as well:
HOOKS="base udev autodetect pata scsi sata usb filesystems usbinput"
And rebuild the image:
# mkinitcpio -p linux
Try not to run any file indexers. I set up a CF card laptop for a friend, running gnome. Trackerd literally ate the drive, even after I excluded /. Uninstalling tracker worked fine, nothing seemed to depend on it.
What about that emergency partition I was taking about? In short, things will go wrong if you are using cheap flash cards. You'll accidentally eject the card, while it's on. You'll shut down and something will get corrupted. And the card is formatted ext2, not the most advanced FS. I've even had cards catch on fire the moment they were powered on. The emergency partition holds a small OS for when things inevitably go belly up, to pull files off or run fsck. My personal favorites are Rescue Is Possible Linux, Puppy Linux, TinyCore Linux, Parted Magic or the Arch Linux installer. Look at them all, find one you like. If installing live-CDs to a drive is too tricky, install one using unetbootin.
And back stuff up! The flash cards are relatively small compared to hard drives, so this is a snap. I usually replace/upgrade my cards every year to be safe, but one did die after just three months.