It'd be handy if the text viewer plugin had the option of showing the contents of csv or tab-separated text files in columns.
Would probably make sense as a separate plugin. Could be a fun, small project for someone...
There was CSV-Viewer (table form layout) (32-bit only) made by a user in the past but it was never updated for 64-bit, unfortunately.
It's also a shame that Excel's preview handler can't handle CSV files. That surprises me every time I need to view one.