It is really hard to get your mind prepared for all the languages you learnt, especially when you haven't been using lots of them for long.
I guess for natural language students, that would be a big problem. Although few ones will have to know quite a many natural languages...
But as programming language/technology learners, one of our missions is to make laziness a virtue, and... we are lucky to have those cheat sheets to help us do part of the job.
Here is a list of collections of tech cheat sheets, which, in my opinion, can be called """the cheat sheets' cheat sheet""" o(∩_∩)o...
TechCheatSheets.com
Cheat-Sheets.org
RefCards.com
'Cheat Sheet Index' on scottklarr.com
'Cheat Sheet Roundup' on petefreitag.com
'Cheat Sheet Round-Up' on smashingmagazine.com
'Cheat Sheets' on addedbytes.com
'Quick Reference Cards' on digilife.be
'Our Favorite Cheat Sheets' on whatis.techtarget.com
Cheat-Sheets.org
RefCards.com
'Cheat Sheet Index' on scottklarr.com
'Cheat Sheet Roundup' on petefreitag.com
'Cheat Sheet Round-Up' on smashingmagazine.com
'Cheat Sheets' on addedbytes.com
'Quick Reference Cards' on digilife.be
'Our Favorite Cheat Sheets' on whatis.techtarget.com
If you know some other good cheat sheets collection, just leave a comment below. Enjoy it~