Which one of those should I spend my time learning to be able to make cool Web 2.0 apps?

I have all summer to do whatever I want- so I ve decided I m going to teach myself another coding language (I already know PHP- HTML- CSS). I want to be able to create rich Web 2.0 like sites for lack of a better word. What coding language is best for this? AJAX?

I have wrote a small ajax chat application (shoutbox). You can see and test it here

http://spacegirlpippa.co.uk

But it doesn t work fast enough for now ...... and sometimes it becomes frozen for a moment (in Mozilla). Please give me a hint what can be the problem- and tips how I can fix it. I m a bit newbie to Ajax programming- but I m planning to learn it in depth. Thank u for your answers in advance

i bought these seat belts from this company called cj pony online and the seat belts stained my upholstery. any tips on what might help clean it off? i have used ajax and paint thinner neither has worked

Is it just hype? Will Ruby on Rails break through as a major player in Web 2.0 (and I assume Web 3.0- whatever that is)?

Basically- is it worth learning? How does it rank with Python & Django?

I ask because I am on the fence as to which to learn. I am moving away from PHP and want to either learn Ruby on Rails or Python (which would be with Django). My main concerns are AJAX. Django seems to still have some issues but Ruby on Rails looks great... I just don t want to learn the language and 2 years down the line find it to be outdated.