The directory recipes/meta contains most of these "meta" targets that build multiple packages but some of the more useful ones are detailed below:
Build all OPIE related packages and some more for OPIE based usage.
Basic packages to go with gpe-image.
Builds a static executable that prints hello world, then loops infinitely.
Build everything. This takes a long time, a lot of network bandwidth, and a lot of disc space. Can also break your toolchain.
Target to update the "feed" files (Package*) to reflect the current set of .ipk's that exist in the deploy directory. Commonly used after building some packages individually to update the feed and allow them to be installed via a package manager or the opkg command line tools.
Builds the appropriate kernel for your device.