Akismet All in One SEO Google Sitemap Generator Contact Form 7 WP-PageNumbers WP-PostRatings WP-PostViews MaxBlogPress Ping Optimizer SEO Post Link Page Link Manager Adsense Manager
I wouldn't touch Akismet if you paid me. They blacklist and leave no real option to get off of it. http://antispam.typepad.com is what we suggest. Ever have a problem, email and it gets resolved.
When I am putting together a new blog, I think about the plugins that must be installed first and why. The very first plug in I install is the xml sitemap generator. I get the sitemap generated and then submitted to my google webmaster tools. This helps get your pages indexed. Second is a lightbox effect for my images. My blog makes use of a lot of graphics in the post, and the lightbox adds a "professional" effect to the pictures. D13 slideshow is next - and this one takes some time to setup. But in the end I think its worth it. Script enabler to display scripts in my post. This is so I can display certain RSS feeds from my forum in my blog post. And since I do not allow comments on my post, I do not have to worry about spam or anything to control spam comments.
Basically, I got 4 or 5 just from reading forums and then I just waited until a " hey, I need something to do this" moment came and then found a plug-in for it. It's worked well so far, I have 25 or plug-ins active.
As little as possible : Askimet, Canonical URL, WP Page Number, BreadCrumbs, Suscribe to Comment, and may be not all of those if I can make it without.