Is there a way to have a List of tables and figures as one list? Currently I have
\listoffigures \listoftables which generates two lists and starts a new page for each list. What I want is a list that contains Tables and Figures in the same list, numbered in sequence (i.e. the first table should get the number following the last figure at that point), Babel-compatible and KOMA-Script-compatible if possible (I use both). The example command
\listoffiguresandtables should create something like
List of Figures and Tables
1.1 A nice picture caption
1.2 Another nice picture caption
2.1 A caption of a cool table
How to do this?

\let\c@table=\c@figurewill solve part of your problem: it will give a single numbering scheme for tables and figures. Tables and figures will still be different lists.figureenvironment for all cases. If that doesn't do what you want could you say what you want to be different.\let\figure\table\let\endtable\endfigure;-)figureeverywhere then the tables won't have "Table 2.1: [caption]" below them, but "Figure 2.1: [caption]".\renewcommand\figurename{Table}\caption{.....}