Easily let users save your blog entries (or any web page) as PDF files for free with Web2PDF.  Although this service has been available for nearly two years, I've rarely run across any blogs that make use of it or anything like it.  The service does not place ads on your site or in the rendered PDFs and it works even with DotNetNuke's dynamically-generated pages.  To top it off, adding the feature to your DNN site is simplicity itself...
 
 
See It In Action
I think a demo of this free service speaks for itself -- that is, it does just what you'd expect.  Click the button to try it for this page....

The "Creating PDF..." browser window that pops up will likely prompt you with a security warning.  IE users will get a "this site blocked from downloading files to your computer" message with "Click here for options".  Click the message and select "Download File".  You'll then get the normal "Open / Save / Cancel"

Of course, there are any number of free programs that create a "virtual printer" which allows you to easily create a PDF through a program's PRINT option.  This is great for you but is hardly something you'd have your website visitors do if they wanted a PDF of one of your site's pages.  Web2PDF does the trick with a minimal of fuss.
  

Not Perfect
I mentioned a "minimal of fuss".  Yes, there is "fuss".  Occasionally you'll get a "limited resources...try again later" message.  This pops up slightly more often than I'd like but, for a free service, I can't complain too loudly.  So far I've been able to do a refresh and get the PDF delivered within a minute or two following such a message.  Since I expect that my "Save page as PDF" link will only be an occasionally used courtesy feature (and since it's free) I'm quite satisfied to have it function most of the time.  (For anyone who has a serious business need for such a service, the company is ready to sell you a copy you can run on your own server.)
 
There's also one major dealbreaker for non-public sites:  the service cannot access password-protected content.  This means that you can only use it for pages that do not require a login to access.
 
Another item to be aware of is that the service does not take a "snapshot" of the current state of the page contents.  Instead it works by separately browsing to the page and generating a PDF of the page as it appears upon completion of a fresh page load.  This means that you can't, for instance, perform a search and then create a PDF of the search results.
 
 
The PDF:  What You Get
Surprise!  You get a plain PDF file with NO advertising at all.  Even the meta-data hidden inside the PDF file is blank -- no data is set for "author", "title", "subject" or "keywords".  Typically such "free" PDF programs and services will give their product some credit in these fields but Web2PDF plays it clean.
 
Print Background Colors
Besides a "plain" PDF void of unwanted advertising, you also get all page graphics including background colors and background graphics -- you know, the things that often won't print when using the "Print Page" browser option.  With Web2PDF you can generate a PDF of a page and then print it just as it appears in the browser.  
 
Clickable Links
You also get clickable links in your PDF....but only for visible URLs beginning with "http" or "www".  So, if I present a link to the Web2PDF website like this:
 
   Click here to check out the free Web2PDF service!

 ...it will NOT get converted to a link in the resulting PDF.  If, however, I present the full URL starting with "http" then it WILL be converted to a clickable link:
 
   http://web2.pdfonline.com/
 
 
Using It on Your DNN Site
Adding the "Save as PDF" feature is quite simple.  First, sign up for a free account and then use your Web2PDF account to generate the needed Javascript (just one line of actual code and one "include").  The online interface is very simple with only a few options to pick from.  Copy the generated javascript and drop the script anywhere on your DNN page or even into your skin and you're done.  You can easily test out the script with a Text/HTML module.  Also note that you can cancel your free account at any time if you decide against using the service and prefer to not leave your info floating around Web2PDF's servers.
 
 
Statistics
The Web2PDF folks were nice enough to provide a "Report" page with nice set of basic stats.  these include all of the URLs that have been converted, whether the conversion was a success or failure (remember that "limited resources" error message I mentioned?) and even the date and time of each conversion.
 
That's great except that you have to log into their site to see the stats -- there's no way to auto-retrieve them.  Worse, it appears that someone hasn't been eating their Wheaties because at certain points you're limited to getting reports only for the year 2007 (the year the service launched).  That's less than useful to put it nicely -- a clear case of "get what you pay for".


Other Uses:  Offer your site as a PDF archive
If you have a mind to, this service allows you to easily archive part of all of a website page-by-page as PDF files.  If this idea is appealing then you'll be interested in a couple of free tools.  The first is "PDF Split and Merge" which is an open-source program to, you guessed it, split and merge PDF files.  Use it to merge your individual webpage PDFs into a single PDF document.
 
PDF Split and Merge (open source)
http://www.pdfsam.org/?page_id=32

Another free tool is the uber-simple "InfoChanger" tool from A-PDF:  This program lets you view and edit the most basic of meta-data for PDF files (author, title, subject and keywords) so you can "brand" that single website archive PDF you compiled with the Split and Merge tool...
 
A-PDF InfoChanger (freeware / donateware)
http://www.a-pdf.com/infochanger/index.htm

 
 
Summary of Web2PDF
The high notes:  Easily give your users the option to save any publically-viewable web page as a clean, ad-free PDF.  Works with DNN's dynamically-generated pages and you even get basic stats broken down by page and timestamps.
 
The low notes:  Service is not 100% reliable.  Service can not access protected content.  Bugs in statistics reporting hint that the service has possibly been ignored after it's 2007 launch with little or no additional development.
 
Bottom Line:  It's free, simple, works more often than it doesn't and is ultra-easy to add to (or remove from) a web page.  Worth every penny!