Here’s a collection of most useful blog add-ons or extras that can be easily integrated with any website and will help in enhancing your visitors’ experience.

All these 15 add-ons are free and you don’t have to be a geek to use them on your site.

gtalk 1. Google Talk Badge – This badge will enable site visitors to get in touch with you quickly. They won’t need a Google account and the badge is enabled only when you are online. Alternative is meebo me.

save_as_pdf 2. Web2PDF Online – Love this. People can download your articles as PDF files with a click. The PDFs are free of any advertising and you also get full access to stats so you know what articles downloaded most, etc. (example)

zohocreator 3. Zoho Creator – If you ever need to create web forms for your blog, use Zoho Creator. It lets you customize the form layouts, there are no data limits and best of all, readers can upload file attachments while submitting the form.

print 4. HP Blog Printing – This makes your blog printer friendly. Visitors can pick blog posts that they want to print and only the text + images get printed. Everything else including banners, sidebars, etc. are cut off from the printed version.

rating 5. Outbrain Ratings – The is the best way to add ratings to your blog posts. Outbrain offers two extra advantages as well – your readers can find more stories related to the one they are currently reading and two, they can rate stories even from feed readers.

feeds 6. ShareThis or AddThis – They help reduce clutter on your blog by neatly arranging icons in a CSS drop-down that appears only on mouse hover. Both are similar though I prefer AddThis as it is loads faster and allows branding.

7. Google Feed Wizard – This is useful if you have to embed RSS feeds in your blog – you can create blocks in either horizontal or vertical format. If your need options other than AJAX, try these RSS widgets or the static Google Gadgets.

vote 8. Skribit – This is again a great tool to get feedback and opinions from your site visitors.

For instance, you can put up a question like "What should I write about" or "How Can I improve" in the sidebar and readers can add opinions anonymously.  They can even vote on suggestions left by other visitors. See example.

visitors 9. who.amung.us – This helps you and your readers know how many people are currently on the site and what pages are they reading.  No sign-up required and amung.us will even tell you the exact location of different visitors on a map.

eco 10. Eco Safe Badge – This badge allows website visitors to send a full copy of your web page to any email address in HTML or PDF format. Alternatively, they can download a PDF version of the page in a click. The whole idea is to discourage visitors from printing web pages.

meebo 11. Meebo Rooms – This allows visitors on your website to interact with each other inside a chat room. Other options worth exploring include Google Lively but again, Lively requires installation at the client’s end.

scribd12. Scribd iPaper – If you frequently link to PDF files and Microsoft Office documents like doc or xls, the Scribd iPaper add-on will make sure that your content remains accessible even to readers who don’t have Microsoft Office or Adobe Reader.

You simply copy-and-paste a small block of code into your webpage, and QuickSwitch converts all the documents in your blog into Flash Paper format hosted on Scribd. If you only link to PDF files, try PDFMeNote script.

media 13. Yahoo! Media Player – If you have an audio blog or frequently link to MP3 files, integrate the Yahoo! media players in your blog template – this auto-detects any MP3 links and creates an embedded player so you are saved from all the hard work.

translate 14. Translate Gadget – This lets your non-English speaking visitors translate articles from your website in their native language using Google Translation.

Alternatively, you can create your own translation box with language flags or through a different translation service.

digg 15. Digg Your Blog – A good Digg widget that doesn’t get much attention.

Unlike the regular "Digg This" buttons, this widget creates a list of posts from your own blog that are currently getting votes on Digg. Put it in your sidebar to highlight "recently popular" content.

Also see:
1. How to Completely Test Your Website 
2. Everything You Wanted to Know about a Website