The "Computational Science" and "Computer Science" Stack Exchange sites have the same exact logo ("CS" in a blue speech balloon). Cryptography and Code Review do as well ("CR" in a blue speech balloon). This is bad for bookmarks, especially when one identifies them only by their logo. This should be remedied, especially since they cover similar topics.
Computational Science is now
Computational Science (a.k.a. scientific computing)
This will probably crop up more and more often as SE plods on. As Ephraim noted, Codereview and Cryptography also have the same logo.
Though out here, Cryptography is
Stuff I can think of
Note that these sites are in beta for just