It would be great to have file manager support in addition to the image manager for the HTML editor. Some sort of way to upload resources, organize them, crop (for images), and ultimately select from a picker to be included in the HTML markup. 

I'd like to be able to have a very compact validation message - just the icon, and a TITLE that is visible when the user hovers over the ! icon.

There should be an event on the validator to be notified when validation triggers.

Would be nice with some sort of table support in the rich text editor. Normally we need a very stripped down RTE since it only represents a part of a page (a block), so the bells and whistles of tinymce are a bit overkill.

However it seems that even though it might be difficult to use in an RTE due to complex UI, we often get questions regarding how to insert a table into a text. Not a complex table, but just a simple table with maybe a class, some th and td's.

It would be really nice if we could stop integrating tinymce and just stick to one library, with a little more beefier RTE in Kendo UI. :)

Ability to use template apposed to field(s) in dataTextField and dataValueField. This feature will make control more flexible and customizable on client side. 

I'd like to be able to... 
- toggle columns on and offer
- filter the content (eg, show only the rows where the Size column is "Medium")
- re-arrange the columns into a different order
- resize the width of columns

Provides a easy way to filter a list with a simple client-side search feature (example add data-filter="true" attribute to the list). The framework will then append a search box above the list and add the behavior to filter out list items that don't contain the current search string as the user types.

We need a pager beyond the grid guys. Did I miss this one? Honestly Kendo Widgets would be good enough so we could build our own components for things like this.

Neither I nor anyone at my company can get it to work. We get a link in a email and the page fails to load at all. That means that I can't get a demo version of the project, I can't post in your forums, and I can't contact technical support. And you don't have a phone number on your site, so I can't contact you that way. If the only way of getting to you is via registration then you really need to make it work properly.

It would be a very cool thing to have a small WYSIWYG-Editor for mobile devices.
As far as I know, there isn't kind of this on the market at all.
So Kendo UI Mobile could be at pioneer-state

Create light-weight Diagram visualization control/wrapper.It may integrate with Telerik's Silverlight/WPF RadDiagram framework.
http://www.telerik.com/products/silverlight/controls/diagrams.aspx

T4 Templates to slect in the asp.net Wizard to provide views controllers and and data connections to services

Currently if you append or insert to an object that uses a datasource (such as grid or treeview), none of the existing entires will have the template applied. This is a major problem and should be resolved ASAP.

It would be great to have a true Timeline control for showing events overtime on a scrollable axis.

Grids correctly display aggregate information in a groupFooterTemplate, but it only shows this information when the section of the group-by is visible (not collapsed).

Is there a way to display the aggregate information in a template that shows when that section is collapsed?

It would be great if it is possible to disable certain dates in the calendar. Maybe if it is possible to pass an entire array with calendar-date-objects, it would be more convenient to disable dates or highlight certain dates.
e.g. CalendarDateObject could have 3 properties:
- CSS class (this style would be applied to that certain date)
- Disabled true/false; default = true (if disabled, date is not clickable)
- Footer text (When you hover over the date, you can see this text in the footer)

By using an array of objects, you don't have to check if a date is in a certain array to change the CSS-class of that date. In the way it is now implemented, you have to write all lines of code to check if the date is in an array.

The forum is great but missing some critical features.

- Search a specific Topic area "Kendo UI Framework" or forum like "Data Source"
- Active Threads (show threads updated to today or since last visit)
- More notification options

It would be great if the chart control was able to produce a radar or spider chart, currently we have to use Silverlight to deliver this feature in our solutions. 

Add documentation for each significant versions. I should not need to always update to latest Kendo UI each time I need to fix or improve something on already shipped app. I know most things are backward compatible, but keep in mind that not every time we can afford the time to update it.