Is not really intuitive how can you add a reference to a css stylesheet at runtime in ASP.NET in the HTML head section: you need to call the page's ClientScript manager and register a Javascript script block defining your script code as a link tag. Remember that RegisterCssReference method will only work if you call it before the page's OnRender event method, so use it in OnLoad and OnPreRender page's events.

The original post can be found at platinumdogs.wordpress.com. 
Visit this arcticle at CodeProject if you need a deeper introduction to SharePoint Web Part's lifecycle events.

This post describes the lifecycle events of a Sharepoint Connectable WebPart wih a single ViewState backed property;

On Page Load

• Constructor
• OnInit
• OnLoad
• ConnectionConsumer method is called if web part is connectable (sets the connection providers interface in the webpart)
• CreateChildControls
• OnPreRender (if your web part is connectable you would typically call the connection provider here to retrieve data)
• SaveViewState
• Render
• RenderChildren
• RenderContents

On 1st Postback

• (PostBack click handler sets ViewState via public Property)
• Constructor
• OnInit
• CreateChildControls
• OnLoad
• PostBack click handling
• ConnectionConsumer method is called if web part is connectable (sets the connection providers interface in the webpart)
• OnPreRender (if your web part is connectable you would typically call the connection provider here to retrieve data)
• SaveViewState
• Render
• RenderChildren
• RenderContents

On 2nd Postback

(PostBack click handler sets ViewState via public Property)

• Constructor
• OnInit
• LoadViewState
• CreateChildControls
• OnLoad
• PostBack click handling
• ConnectionConsumer method is called if web part is connectable (sets the connection providers interface in the webpart)
• OnPreRender (if your web part is connectable you would typically call the connection provider here to retrieve data)
• SaveViewState
• Render
• RenderChildren
• RenderContents

Note that during the 2nd postback, LoadViewState, is called, since in the 1st postback the click handler sets the value of the ViewState backed public property. 
Credits for this post goes to Phil Harding. Thanks Phil for sharing. 

Based on this post founded in Path to SharePoint, I have created a SharePoint Web Part called SharePointOpenCloseWps that once installed in your SharePoint page, it let’s you choose which Web Parts you want to make collapsible. The OpenCloseWps allows you to choose what web part should be collapsible by configuring OpenCloseWps’s property named “Web Part names to make collapsible”. In this post you will find the source code and the intaller.
The solution is built using Visual Studio 2008 and WspBuilder (if you don’t know what is WspBuilder, get it and try it!) and can be easily installed running a batch file.

Installation

Download the sourcecode and navigate to “\SharePointOpenCloseWps\bin\deploy\SharePointOpenCloseWps”, run deploywithstsadmOnLocalhost if you want to install it on http://localhost/ or edit the file and add your SharePoint site’s url. Once the batch has completed, go to your “web parts gallery” under your site collection’s “Site Settings” , clicck new and add OpenCloseWps.webpart:

Next, go to your SharePoint page, add the web part, and edit the property named “Web Part names to make collapsible” under Settings. Insert the titles of the Web Parts that you need to make collapsible and press Apply:

The OpenCloseWps will load the necessary JavaScript code to perform the trick and your Web Parts will be fully expandable / collapsible:

Please note that only one OpenCloseWps is allowed in the same page. If you have questions let me know..

Download OpenCloseWps SharePointOpenCloseWps20090422214413.rar (503.89 kb)

Why should you pay for a chart program if you can geti it for free?
Autodesk published an impressive web application completely free to let you draw you own charts online.  Project Draw allows you to do everthing you need:

http://draw.labs.autodesk.com/ADDraw/draw.html

You don't need to have a product serial number to use all the features: just create an account and skip the last step where you are asked to provide the key:

 https://registeronce.autodesk.com/eidm/selfcare/beginSelfRegistration!input.action

Don't forget to register and press ctrl + d once you have visited the link