[iheartmemcache]

Not bad, especically for the EE, Physics people. But most of these abstractions are pretty intuitively modelable in ones head. There are better Fourier transform visual models, which I'd argue is in the top five of least intuitive concepts one would encounter in the standard courses up to 200 level. I can imagine this being helpful for kids taking AP classes, but there's a real dearth of resources for visualizing higher-level course material. Like, amplitude, phase, the standard electrical engineering constructs made with passives (RLC, RC tau, cap charge and discharge), heat distribution, these are all fairly intuitive, no? All resources are considered a net positive in my book, but there are better resources out there, e.g., I think BetterExplained has a way better intuitive way of approaching linear algebra that even "non-math people" can 'get'.

[skeuomorf]

I think some (most?) of these mathlets are used in conjunction with MIT courses [0], for example it's used in [1] with an assignment so that it develops the intuition of the student solving that assignment.

[0] http://mathlets.org/courses/

[1] http://ocw.mit.edu/courses/mathematics/18-01sc-single-variab...