The name fits...this 3-year-old site offers a web-based calculator with 400-plus calculation options. It does not replicate a standard calculator's operations on numbers. Rather, if you or your students are connected to secondary mathematics, some of the "mindless" calculations being done could be done by this calculator. Also, the site offers opportunities to explore some new mathematics.
For example, in algebra, the site solves equations (linear, quadratic, cubic, and quartic), finds GCMs and LCDs, and computes factorials. As a side exploration, you might explore the site's computation of values for things such as 1.5! or (-2)! and try to determine what the computed values mean and even moreso are they correct....i.e. BEWARE!
In geometry, the site computes the standard measurement items (areas, volumes, surface areas), but also includes things you can explore such as the computation of the area of a generic quadrilateral using either Brahmagupta's Formula or Bretschneider's Formula...first, investigate via the Internet what these even mean.
In the "Math Miscellaneous" section, the site performs divisibility tests and factors numbers (seems somewhat redundant to have both of these options), prints out subsets of the Fibonacci sequence, and draws a fractal tree that is more magical than useful.
As expected, the site includes a multitude of calculation options related to science (including unit conversions), finances, computer programming, health/fitness (e.g. BMI and BMR), medical calculations, sports, home energy usage, and the unexpected Star Trek Warp Factor.
And last, the site offers sections labeled as "Fun and Games" and "Miscellaneous," with both offering options that will prove to be entertaining. A few examples include a reflex test, a mind-reader, a love calculator, an unusual penny calculator, a playoff chart maker, and the bizarre value of beating a train.
For those who are interested, the creator of the site also offers free-access to a forum (browse through it for some interesting observations/questions) and a free e-mail newsletter dealing with web calculator issues.
Source: WebCalc Site link