Ideas

This program uses weather data supplied by the Weather::Underground module to create an ASCII animation that simulates the weather. There is also a large number of random creatures and objects that walk across this screen. As of version 1.7, I've begun adding seasonal/holiday objects.>Source: WeatherSpect
From an idea: DARE Vancouver
Adding ASCII art to the source code (the HTML files) may not interest people who don't look at source code. The source code is an easy place to add ASCII art because those files open in plain text, no formatting or fancy fonts. So, the ASCII art shows up without much extra work, almost none in fact. If you access your HTML files you can add ASCII art yourself, without the plugins. (See above). But, not everyone wants to do that.

WP Figlet

WP Figlet is all about adding text created in ASCII art fonts (figlets). It even lets you choose which figlet fonts you want to use. The auto suggestions creates a figlet in your source code like this (you choose your own words): It does work.

Source Code ASCII Art

Source Code (although not updated in 4 years, also works). If you are timid about mucking around in the HTML files then either of these plugins will work for you. Source Code lets you choose to have the ASCII art in your header or footer. However, I found it did need the extra HTML code for keeping the formatting after I saved my text image. One thing I dislike about Source Code is the lack of artist credit (artist initials). I checked several of the ASCII images available with the plugin and none had artist credits. I used my own ASCII image with my initials.

In the end... DIY.

Don't be bashful about getting into your own source code. Skip the plugins and just do it yourself.  Once you access the file it's very simple to add the ASCII art with the code for notes. (See the first image in this post, no reason you can't do that yourself).
I looked at 3 plugins to add ASCII art to your WordPress blog. This is the first one I loaded up and experimented with. It does work but may not be the results you wanted. There are no options to add the ASCII art to the bottom of your posts or pages. The plugin does place ASCII art at the very bottom of my site, under the footer.  Below is my first experiment. I was pretty neutral with the results. But, I'm a bit traditional when it comes to the font I use. The spacing was out, the lines between text. Also, the top line of my art was pushed to the left. I tried another ASCII, thinking a longer image would look better either way. Adding HTML code worked to keep the formatting but, it shows up on the site. Still it is nice to have a little surprise for anyone who reads to the end. So I will keep this plugin and see how often I remember to change out the ASCII art images.
via - Humans TXT: We Are People, Not Machines. - Word Grrls
via - Claddagh Ring With or Without a stone by Ricksonjewellery. I like this update on the Claddagh design. I wanted to make a Claddagh with ASCII art and may use the hands in this way. Much easier than showing all the fingers (hard to get narrow lines that close together unless I make the Claddagh in a pretty large size). I found a crown on another Claddagh which I like too, a vintage ring I posted to Pinterest.
Litographs: Pick your book, choose colours and whether you want a tote bag, poster or other and you can have your favourite book (or the one you're reading now) created as text art from the text of the book. I especially like the creativeness of the designs. Some really take the story of the book and show it very well in just one image. link via - Book-themed lithos/tees with entire text of books - Boing Boing. I found the link in a post on Boing Boing. See above for the actual site link.