Q:

Passing argument to custom SharePoint list form

Is it possible to pass column data as query string to custom dispform.aspx when view item is clicked ?
For example, if my custom display form name is MyDispform.aspx and when list item is clicked it will open my display form like MyDispform.aspx?user=participant where participant is the column name of the item.

A:

Yes, you can do this.  You will need to use some custom XSLT to create your link but it will be something like:
<a href="MyDispForm.aspx?user={@Participant}"><xsl:value-of select="@Participant" /></a>

Then, as indicated by Paul you will need to make sure your custom form does something with the parameter.

