Notepad++, the best Notepad replacement. Has regex find+replace, find in files+repace, syntax highlighting for many languages, lots of line operations, EOL conversion operations, tons and tons of goodies if you look under the right click, Edit, Search, TextFX (if it doesn't come with TextFX plugin, recommend you install it!) and View menus. I recommend you look through all the menus and familiarize yourself with what time savers it can do even if you use the program a lot, I guarantee you're overlooking something cool you can do with it. For example, you can do a search, have notepad++ mark all lines that match the search, invert marking (mark -> unmarked, unmarked -> marked) then do something with all marked lines (delete for example).
SpeedCrunch is a calculator and can be an alternative to PowerCalc. It has variables and a bunch of useful functions, many that powercalc is missing (including but not limited to: factorial, mod, and, or, xor, not, oct, bin, hex, all hyperbolic and trigonometric functions and inverses, gamma, erf, lots of probability functions, min, max, average, abs, arithmetic shifts...). The main feature missing from it that I liked about PowerCalc is user-definable functions, but if you're going to build a big, crazy function or program, you may as well cut out the middle man and open a Python or LUA interactive prompt at that point :)