Aaah yes. Six months ago you discovered the prototype and scriptaculous javascript libraries. You've put together a sexy drag and drop demo with Ajax requests reloading content on the fly and convinced upper management that you hold the future in your hands.

Then comes the DOM bloating. Your test leads are struggling to automate testing and your dev team is now saying Struts ain't so bad after all.

Relax. Here's some practical advice to ponder before going all in with Web 2.0.

1. Define the business cases which support Rich User Interaction.
Not every web based needs animated transitions or real time lookups. Remind yourself that value is what the customer wants AND is willing to pay for.

2. Know your Front End frameworks.
Open source can sometimes be familiar with 'self service.' Can you afford to figure things out on your own when the first production issue raises it's ugly head? Are you sure you know the difference between Zkoss, YUI, and Jackbe?

3. Get Firebug .
You will thank me later.

4. Understand javascript closures.
Improperly setting up and cleaning javascript entities will eat all of your memory.

5. Understand the difference between Usability and Familiarity
Introducing change into a user's interaction model is not without cost, even if it is in support of a percieved improvement. Screens can get more cluttered and users will become quickly frustrated if your dynamic user interface isn't manageable and predictable.