You should look at the fairly recent txtplot package. Currently, it includes scatterplot, line plot, density plot, acf, and bar chart.
From the online help,
> txtplot(cars[,1], cars[,2])
+----+------------+------------+-----------+------------+--+
120 + * +
| |
100 + +
| * * |
80 + * * +
| * * * |
60 + * * +
| * * * * * |
40 + * * * * * +
| * * * * * * * |
20 + * * * * * * * +
| * * * * |
| * * * |
0 +----+------------+------------+-----------+------------+--+
5 10 15 20 25
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