WP Plugin for this..
 

Whats the best wp plugin to use for redirects. sitename.com/go/here-now or something that I see lots of people doing these days.

http://www.wplinkengine.com/
http://www.prettylinkpro.com/

or if you want something simpler and free...
http://wordpress.org/extend/plugins/gocodes/

prettylink is what i use

what's the benefit of using it?

Shorter URLs, "prettier" URLs, less chance of losing commissions to malware, visitor can't hover over the link and decide he's not going to click because he sees an affiliate link.

wplinkengine is better than prettylink

Does anyone know if there is a WP Tag Redirect plugin? Similar to this, but for tags.
http://wordpress.org/extend/plugins/...-post-or-page/

I like the cat redirect because you can redirect to custom landing pages. So if someone clicks on a cat link for 'British Porn Stars", it will go to a page devoted to British porn stars instead of a page that resembles WP search results page showing other British porn star related posts. Likewise, I'd like to have a tag redirect so if someone clicks on "Lolly Badcock", it will go to a Lolly Badcock landing page.

hiding afiliate links