Most of the suggestions are for a single solution that handles both simple and complex table needs, with the complex end of the scale being pretty messy, no matter what the particular syntax.
Although this goes against the OneTrueWay to do anything, I'd suggest having both a "simple table" markup and an "extended table" markup.
The simple table would cover, I believe, many editors' needs while keeping the syntax very easily editable by anyone.
The extended table markup would only come into play where the editor thought that formatting needs overrode easy accessibility.
Simple Table: (view this with a fixed-width font, if possible)
">" in first physical column to indicate row "|" to delimit table columns; doesn't have to start next to ">" not ">" in first physical column indicates end of table
| cell1 | cell2 | | cell3 | cell4 |
| new table | content here | another column | | blah | blah | blah blah |
*possibly*, let spaces around "|" indicate alignment: |left-aligned | (text touching only left bar) | right-aligned| (text touching only right bar) | centered | (white-space on both sides)
so editor could still align bars for good visual effect in the edit box, w/o a lot of special alignment markers to clutter up content
Extended Table:
(one of the complex schemes proposed or to be proposed)
loh