Try gnuplot:
gnuplot> set terminal dumb
Terminal type set to 'dumb'
Options are 'feed 79 24'
gnuplot> plot sin(x)
1 ++----------------**---------------+----**-----------+--------**-----++
+ *+ * + * * + sin(x) ****** +
0.8 ++ * * * * * * ++
| * * * * * * |
0.6 ++ * * * * * * ++
* * * * * * * |
0.4 +* * * * * * * ++
|* * * * * * * |
0.2 +* * * * * * * ++
| * * * * * * * |
0 ++* * * * * * *++
| * * * * * * *|
-0.2 ++ * * * * * * *+
| * * * * * * *|
-0.4 ++ * * * * * * *+
| * * * * * * *
-0.6 ++ * * * * * * ++
| * * * * * * |
-0.8 ++ * * * * * * ++
+ * * + * * + * * +
-1 ++-----**---------+----------**----+---------------**+---------------++
-10 -5 0 5 10
or this:
http://wdas.github.com/SeExpr/doxygen/mytut.html[
^]
./asciiGraph "val=.5*PI*x;7*sin(val)/val"
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###
# |#
## |##
# | #
## | ##
# | #
## | ##
# | #
# | ##
#### # | # ####
#######-----##--###-----#-----|----##-----##--###-----######
###### ## # | # # ######
## ## | ## ##
### | ###
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I know you said VB. Net, but we can't spoon-feed you :)