Laurasia already has traders to allow you to "cash in" 10, 30, 60 or 100 levels and obtain a matching amount of XP bottles in return. This gives you a chance to store levels for later use, or use your current experience points to repair any equipment with the Mending effect on it. As a reminder, in Laurasia, you'll find these in the basement of Doctacosa's Study, at the Creeper Citadel. There's also an option to cash in 200 levels to obtain a Merit Voucher.
To get the other survival servers on the same footing, Rodinia and Gondwana (which have separate experience levels) now have their own traders as well. In Rodinia, visit the basement of the Community Center at Point Zero. In Gondwana, you'll find them at Keystone City, at the left of the stairs from the spawn point.
Along the same lines, the special book to customize armor stands can now be obtained directly in both Rodinia and Gondwana as well, next to the XP traders. Remember that what we've taken to calling pixie dust books are fragile: if you disconnect or change worlds while holding one in your inventory or ender chest, it'll become unusable. Your best bet is to get a book per world then store it somewhere in a regular chest. If you accidentally break one, burn it and go get another copy.
On the topic of science areas, new reference topics have been added to the forums recently. The trades offered at Moosemart are now listed, plus the list of items displayed in the Cavern of Science. The Challenge Areas listing is still available, of course.
Additionally, Twixxi made a reference with all the Public Farms available on the servers. If you know of one that wasn't included, get in touch with her!