Hi Manny,
DataGrid and GridView are server controls, you cannot add server controls into html markup.
If you mean a list of all the h1 elements within the blog post, I do not know a way to automate that offhand. You could probably implement something with jquery but a javascript solution would only work on the site it would not work in the RSS feed for users who subscribe via feed readers like google reader.
I would also point out that really within a blog post you should start with h3 because the site title is h1 and the title of the blog feature is h2. Note that in CKeditor and FCKeditor we alias h3 as h1 so when you choose h1 it is really h3. We do this to encourage the correct structure, however if using TinyMCE we don't have a way to alias it so h1 really is h1 in that editor.
Additionally, a table is not a good choice for a table of contents, tables should only be used for tabular data. A list of of headings would be better with a ul or ol that links to anchor tags at the heading elements.
Unfortunately I don't know of a good way to create that other than manually.
Hope it helps,
Joe