The grid has a number of built in filters, what is not supported is searching for cells that have no value or some value (i.e. NULL or NOT NULL).
This would be a very useful addition.

I'd like to see an event for Grid contents modified (after-edit or after-add/delete, etc).  This would enable a sync with a DataSource, for instance, without further user action.  Presently, this is not easily achieved.

It should be possible to change the width of a grid after it created.
http://www.telerik.com/forums/change-column-widths-after-grid-created

Add Min Width Property to Grid Column so that a user can't manually shrink a column beyond a certain width.

Ability for a grid to show foreign key values from a remote datasource rather than just a fixed array.

Refer to: http://www.kendoui.com/forums/ui/grid/foreign-key-option-doesn-t-work.aspx

The event args from column.groupHeaderTemplate (and groupFooterTemplate) should contain a function to retrieve the data for that group. Currently, they only contain "field" and "value." If you made the grouped rows available in this event, clients would be free to add multiple aggregate columns of the same type (i.e., get the "sum" of multiple values instead of being limited to a single value). I've been able to halfway implement this, but it only works correctly if I'm only grouping by one column. For example, if I'm grouped by WidgetName and then by ProductCode, my event args for ProductCode should contain a function to return data rows for only rows matching the current ProductCode and WidgetName.

Currently we do not have the ability for descending to be first. It's either one, both in the asc/desc order, or none. You can changed the setting in the kendo javascript file but it'd be useful to have it be a property.

There is an option to freeze the left most column of the Kendo Grid by setting the lockable property.
But this is limited to the Left Hand Side columns only and there are no ways suggested to freeze the Right Most columns.

See this Kendo Forum post:
http://www.telerik.com/forums/multi-select-in-responsive

In short, we need additional approaches to grid multi select using touch events

http://www.kendoui.com/forums/ui/grid/pager-controls-should-be-hidden-when-total-results-is-less-than-the-pagesize.aspx

Right now there are two options for sorting, single and multi-column. We would very much like to use the multisort version, however our users fail to understand the functionality. We suggest a new setting, "ctrl-multisort":

Single-sort when clicking and multi-sort when ctrl-clicking, similair to most desktop grid controls.

Excel-like filter always show all available options.
When one filter was already applied  - could we limit number of options to see only options that are left after previous filtration?

We should be able to filter only by already filtered rows.

As alternative - could we have some event on Excel-like filter to populate options for it every time it expands?

Currently we use batch editing in the Grid control. The idea of batch editing is all changes are retained client side until the user presses the save button. 

When editing a cell a red dirty indicator is placed on the cell. This gives the user an indication that there are unsaved changes. however, when deleting a row, the row just goes away. There is no indication the user must still save. 

I would like to see rather than the record immediately removed a class applied to the row so we can apply some style like a strikethrough or red background color to indicate a pending delete. Also, we would be able to switch the "delete" button to an "undo" button.

Currently Kendo UI grid don't have any way to know that grid changes its mode from edit to view in case of incell editing.
As per thread (http://www.telerik.com/forums/is-there-any-way-to-know-grid-edit-mode-changes) we have to add blur/focusout event handler to know changing mode. But some time it happen (in case of adding custom widgets through columns editor) that blur/focusout event triggered but still grid is in edit mode.
Its better to have an event when grid changes its mode from edit to view so that we can minimize issue mentioned above.

Currently if you add a row to a grid in batch edit mode any rows that have already been edited will lose their dirty flag indicator.  I would like for Kendo to handle maintaining the dirty flag for these rows.  If there is a performance concern with adding this functionality, then maybe there could be a setting to turn it on or off.

include checkbox-based selection in the grid and allow the persisting of selections in paginated grid (i.e. user selects rows on page 1, switches to page 2, returns to page 1 --> previous selection is restored)

When using Grid with virtual scrollbar there is no possibilty to go to sepecific row programaticly. Especially for row that are not yet loaded.

I have managed to move the scrolbar using 

grid.virtualScrollable.verticalScrollbar.scrollTop(scrollRow[0].offsetTop + pageOffset * pageIndex);

however the calcualtion of the location of the row is impossible when rows have dynamic height.

It would be nice to have the possiblity to toggle edit mode on and off for the Grid.
Use case: Often users find things that need changing whilst browsing data. In those cases it would be nice to have a toggle button in the toolbar that enables and disables edit mode. n quiting edit mode the users

Personally, I much prefer image buttons over text buttons in the grid just to keep bulk down especially when you have a wide grid or a number of custom command buttons with long text.

To do this at present requires some fancy css styling in the grid databound event.

I would like to see more configuration options for grid commands to allow for ....

- Built-in commands (Edit, Delete, etc) and custom commands to be image only
- Built-in commands and custom commands to have a "tooltip" option

Very often in grids we want command buttons disabled (or not even visible) depending upon model data, such as Delete not being available if the data has certain values set. Something like:

columns.Command(commands => {
  commands.Edit();
  commands.Destroy().VisibleIf(model => model.IsPosted)
  });

Using HtmlAttributes would be acceptable if it was easy to access the model. I'm currently achieving this by using a client template and rendering the buttons myself, but this seems overly complex for what is a simple occurance.