First, i don't code anything myself (lack of time and mostly skill) and therefore don't want to demand anything, i don't think i have the right to. But as i watch the development of KDE4 now since about a year and i'm amazed i also want it to become that good, that everybody wants to use it.
So what i want to see is acctually nothing specific but in general features that ease the use of the computer for the normal user.

I'd like to give some examples to make it clear.
Some minutes ago i found this thread:
showthread.php?tid=10036
Nepomuk is an great concept, i like to see more of it, but for the moment it seems to me, all i can do is rate files with dolphin and tag them. This only takes time and i see no gain in it for the general user (there will be a search for meta tags, this will bring a use for them) I think it would be a huge gain if a lot of applications would automaticaly create metadata, and then the user could search it! You could search for files downloaded from the net/a website or which where send you per email or im. (This is not a new idea, not my idea)

Also missing: Decibel
There may not be that much facilitations with decibel in contrast to kopete (or things you could not do with kopete but with decibel) but i like the idea of a daemon which runs in background, displaying IM information where i need it at the moment (user online status in KMail?)
Possible features: - send url/pics/text passages out of konqueror directly to IMBuddys (Buddys you chat with in a contextmenu?) could save the "select url, copy paste it, send it" time
-fileshare over IM with context actions in Dolphin
-let buddys listen to your music, if you want to show them a song (http://bugzilla.gnome.org/show_bug.cgi?id=526499 also not an idea of my own)

Plasma:
I love plasma, i really do (build the whole trunk every week and play a bit)
Everytime i tried to switch to KDE4 (using Gnome right now :-$) i began to play with the plasmoids and ended up with .. eyecandy on my desktop
I don't want to sound like i know anything better, i don't really have an idea what to improve on plasma. I think the technologie is very good (maybe perfect) but now there has to be a way to use it to build a better desktop experience ( http://forum.kde.org/showthread.php?tid=10918 this may be related to my thougth )
Only some plasmoids are in my opinion enhancing your workflow, things like Clocks and CPU Sensors are all nice and needed but do not help me to make less clicks in every session.
Some possible ideas:
-Task list (with akonadi backend) (i think there is already one, but im not sure about akonadi support)
- Upcoming events
- Buddylist
- Inbox
- (and your own idea)


More Akonadi:
- create tasks/termins where they are made (sounds bad), in an IM conversation, in an email you got from your friend, in an PDF invitation, on a website ...
- ..

Another thing maybe usfull: Network
- easy filesharing: if the user has a PC and a laptop/his mom has also a PC/ he should not worry about how to get the files over there, maybe theres a Place in Dolphin which list all availabel PC on the net (even if the don't have filesharing (smb/nfs/idontknow) enabled) and if the run KDE4 you just have to "send" them there and they get placed in a NetworkInbox ?
- keep akonadi servers in sync: i have a laptop and a computer, my imap gmail account is the same on both but if i want to keep a list of tasks? (this may be difficult but deffinitly helpfull)

and so on.

As my english is not that good and my thoughts are not that structured, i like to summarize:
Nothing written above is THE feature i want in KDE4
I think every feature that helps the user to save clicks or time makes KDE4 superior to other Desktop Enviroments
Every feature that does what the user want and provides it in an that intuitve way that the user has done was he wanted befor he realizes how easy it was is an Epic Win
My intention is to share my view on KDE4 features and the way i rate them

Please correct me if i'm wrong somewhere but don't go like "you said this/that can't do this/that and thats wrong 'caus look here , come back with real arguments"
I'm more interessted in what you think about if there is/is not/is not enougth which fascilates the interaction with your desktop
Maybe you also have some ideas, maybe we could make a list of available features (which make KDE4 easier to use as ) and desired features

As a read again what i've written so far i have to admit that some mentioned ideas also are just for fun(TM) but i hope everyone understand what i aime at.
I also hope everything is logicaly clear as i'm not able to express everything exactly the way i would like it in english.

Some thougths that came while writing:
I had two ideas for plasmoids which would really save time for me. An bus/train/whatever lookup plasmoid would help to avoid visiting the website and could save defaults ( this may be very hard to do and not possible for every region as the bus/train/whatever company may not have an webservice, most likely not i think)
An plasmoid that let's me search my Book Library and maybe allow to book a book
Same advantages and problems as above

Now i like to hear your opinion on this

Regarding Nepomuk, A search KIO slave has been integrated for 4.2 so all KDE applications will be able to use Nepomuk ( and thus Strigi ) powered search from the file open / save dialog, and from Konqueror. this will provide a kind of virtual folder support ( a folder automatically filled with matches to a certain search ) which I can see myself using.