Wall crab spider, or "Flattie" (Selenopidae: probably Selenops sp.), from Monteverde, Costa Rica. These spiders were quite abundant, particularly indoors where they took advantage of their low profile to hide under picture frames and posters. I love the subtle mossy coloration on this one.
Wandering spider, Ctenidae, from Monteverde, Costa Rica.
A female wolf spider (Lycosidae) protects her eggs in her burrow on a riverbank in Iowa.