- Include List Data flag, if you enable the checkbox the xml data will include the underscore data (_ListTitle, _ListUrl, _SiteTitle, _SiteUrl, _ItemId, _ItemUrl, _ItemEdit)

- Queries

    -  CAML Query you can use a caml query to search on each list.
    -  RowLimit - maximun number of rows to return
    -  Recursive - the query recursive be made (great for Document Libraries)
    -  DebugQuery - show the xml from the query

   Special values that you can use on queries:

    [Login] - the logged user
    [UserName] - the complete user name
    [UserID] - the user ID
    [Now] - the current date and time
    [Now+x] - the current date and time + x days
    [Now-x] - the current date and time  - x days

  example:

   1:  <query>

   2:     <Where>

   3:        <And>

   4:           <Eq>

   5:              <FieldRef Name="Author" />

   6:   

   7:              <Value Type="Text">[UserName]</Value>

   8:           </Eq>

   9:   

  10:           <Eq>

  11:              <FieldRef Name="Modified" />

  12:   

  13:              <Value Type="DateTime">[Now-30]</Value>

  14:           </Eq>

  15:        </And>

  16:     </Where>

  17:   

  18:     <OrderBy>

  19:        <FieldRef Name="Modified" Ascending="False" />

  20:     </OrderBy>

  21:  </query>

   (Note, you need put all fields thats are on query in the fields property).

- CellConsumer interface, you can use an special value in queries called [CellProvider] this value is replaced with the cell value provide from other webpart.

Sample (conected to a document library)

<Where>

<Contains>

<FieldRef Name='FileRef'/>

<Value Type='Text'>[CellProvider]</Value>

</Contains>

</Where>

- CellProvider interface, you can provide a value to another webpart, any value that you wants, when rendering the xsl, you can add a __doPostBack('','Value') to provide values.

example:

   1:  <a href="javascript:__doPostBack('','{@Name}')">

   2:  <xsl:value-of select="_SiteTitle"/>

   3:  </a>

I have a Release Candidate version if somebody wants test it, please comment this post, thanks.