As a follow-up to the post on chess software and by popular demand, here's how to use Aquarium 2011 in order to publish a game on a blog. An example of the results can be seen here. Warning: not a user-friendly process.
1. Update Aquarium. Get the latest Aquarium 2011 update from ChessOK. The original forum post describing this is here. Once installed, your web publishing options will now be correctly shown and enabled.
2. Set up your blog style sheets. Once you've loaded a game in Aquarium (any game will do), on the Publish tab select the Web Export - iBook HTML for Blog option. (It doesn't matter if you actually want to publish in the iBook format or not.) The program will bring up a new window with style sheet code at the top and the iBook code at the bottom. Copy the style sheet code to your clipboard (there's a link on the new window to do that for you). This then needs to be added to your blog's template html. As an example, if you're using the latest Blogger interface, you can access this via the Design - Edit HTML option. I suggest pasting the code near the top, just after the line where you see your title section, which should begin with < title >. Then click Save Template. This enables your blog for Aquarium publishing.
3. Publish a game in a blog post (with playable board and game score with annotations). On the Publish tab select the Web Export - HTML for Blog option. This brings up a new window with the HTML code, copy this to your clipboard. In a new blog post, when you are ready to paste the game in, make sure you are looking at the HTML rather than normal text (Blogger has "Compose" and "HTML" buttons, choose the latter). Paste in the HTML code where you want the board and attached game score/annotations to appear. To avoid having a lot of white space above your chessboard, under Post settings make sure the option is chosen to have line breaks use the < br > tag.
There's also a ChessCafe article that covers most (but not all) of the above.
Observations: practically speaking, it's better to have any other text you want in the post above the published game. Also, if you go back in to edit your post after publication, the game board may not function afterwards and you will then need to delete and re-paste the game HTML code. Finally, I've noticed that no other blog posts below an Aquarium game will show up on my main blog page. This isn't a big deal for me, since I prefer only having 1-2 posts on the main blog. Not sure if other users have been affected by this issue, but I spent a lot of time Googling in order to track down what was necessary to get the publishing process to work properly and don't recall seeing another mention of it.