Missing Value Treatment, Outlier Treatment, Type-casts, etc.
Augment (Add New Columns)
Arithmetic Transforms, Running and Time-Window Stats, Shifts/Leads/Lags, Geo-Coding, etc.
Convert to Time-Series
Mean, First, Last, Sum, Count, Max, Min, etc.
Rollup Data by Group
Mean, Median, Sum, Differences, Unique-Counts, Concentration Indices, First, Last, Contents, etc.
Aggregate Attributes, Unique Attributes, etc.
Apply Filters on Data, and make filtered data-sets.
Stack Data to Single File
Files with same columns, but corresponding to different groups, e.g., Year, Gender
Join Data (DB-Style)
Indexed joins (including lookup-style). Inner and Outer Joins. And multiple files.