Several of the logos have eight items, four of which are highlighted in a different color or luminance, representing the 8 bytes native to 64-bit architectures which differentiates them from 32-bit's 4 bytes.

The gnu heads are made from a handful of vector points and are thus...minimalist gnus, get it?

Those last checker pattern logos, in addition to having the 8 squares as mentioned, also look like a pair of overlapping ++s, which could be evocative of C++, arguably one of the more popular languages supported by GCC.

These are not "finished" or "professional" logos. They're just an amateur fooling around for an evening. Perhaps the community can come up with something it likes.

Seeds for brainstorming

Perhaps this list will help get the creative portions of your brains going for logo ideas.