Summarizing software can be a great benefit when doing SEO. I don't know of any that will auto-insert data into a description or tag, but they will generate a clean page containing keywords and concepts that can be used. I use a tool by Copernic that is built into your browser. Any page I'm looking at can be summarized with one click.
Here is an example summary of Brett's Article on choosing keywords:
Selecting Keyword Ranking Gold
keywords, ranking, referrals, optimization, blue fuzzy widgets, conversion rate, search engine, gold, competition, internet, listing, phoney, hit, pull, Alta, selecting, users hitting, ranking spot, low amounts, mass, fail, expert keyword, fun keyword, closely related keyword, word keywords, traffic powerhouses, life blood, major keyword lists, Goto, secret
Summary: Selecting Keyword Ranking Gold
Some random thoughts on the importance of selecting good internet keywords.
There are "unique" and rare keywords that can be gold.
Learning to target and track them can be the complete key to your internet success.
The "blue fuzzy widgets" keywords are competitive and loaded up with optimizers on all the search engines.
What would your competition pay to know that little secret?
If it doesn't really show on Goto or any other major keyword lists - yet it is the life blood of your traffic.
There are unique keywords that are traffic powerhouses.
I know of 4 word keywords in the top three on Alta that can generate a k a day in referrals.
There are also keywords, where a #8 ranking will pull as many referrals as a closely related keyword will at #1.
There are all kinds of fun keyword combo's that go unnoticed by even the expert keyword people.
Most get blinded by pure traffic numbers coming in on a keyword and fail to look at things like, conversion rates and per user click rates.
Some keywords generate referrals in mass number, yet they are all one hit wonders.
Still others generate low amounts of visitors, yet those visitors click around your site for hours.
There are keywords where you can get say a 7-10 ranking that will generate as many referrals as "better keywords" can the top 1-2 ranking spot.
A top 3 listing under "search engine optimization" on Alta will generate about 900 referrals a day that turn into about 4k views by users hitting the site.
A top 10 listing under "search engine rankings optimization" only generates about 300 referrals a day, yet the conversion rate is 1 in 4k views.
So all the competition is fighting over "search engine optimization" while we clean up with "rankings optimization".
Why a phoney example and not a real world?
I've found it to be a very handy tool when it comes to writing titles and tags for long articles.