I started playing osu! on 15th June, 2012. A few thoughts of "It would be better if osu! can..." came out in my mind, and I'm happy to see that some of them are already implemented now. Below are some features I want but unimplemented:
1. Multi-term search
Now in the beatmap search function, you can search the name of the song, the artist, the beatmap author, etc. seperately, but not combined. e.g. You can search "Platinum Disco" for all the Platinum Disco beatmaps in your library, and you can also search "wcx19911123" for all beatmaps made by wcx19911123, but you can't search "Platinum Disco wcx19911123" for the beatmap of Platinum Disco made by wcx19911123. Hope this could be done in the future.
2. Search by beatmap ID
For guys like me who remember the ID of favorite beatmaps well, it's more convenient to type just 5 numbers (or below) than to type the name of the song and selecting from the results. The beatmap ID is unique, so you don't need to select. I think this may need some changes to be done on the osu file format.
3. Hotkey for 4K mod
The 4K mod is on the place of "relax" on the Mod Selection screen, but you can't press "x" to select it. 4K is the only mod that can't be selected with the keyboard.
4. About chat
I often miss some messages my friend sends to me when I'm not seeing the private chatting tab. If the chat tabs are highlighted when new message arrives, no messages will be missed.
5. About skins
For now, skins can only be downloaded officially in the "Extras" tab of the updater. The downloading speed of the updater is quite slow and the skins are also few and I can't find many skins I like. I think it'll be good if skins are dealed like beatmaps on the web, anybody can upload skins, and skins are packed in the extension of OSS (OSu Skin).
6. About beatmap editing
The editor is showing osu! standard mode when editing. That makes it difficult to see if the beatmap looks god in Taiko, CTB and osu!mania. These 3 modes should also be able to be selected when editing.
7. About the "hidden" mod
I think it's quite hard and 1.06x score multiplying is too little. I think a value of about 1.12x is fine.
8. Add "Watch video" mod
I often want to watch the video of a song in osu!, but the circles & sliders covered part of the video and makes it look bad. Project DIVA does well on this.
8. About osu! on other platforms
osu!droid is performing well except online playing. I think online play to be added to make it more fun. Online play can be done when using WiFi or 3G network. Also, Windows Mobile & Java ME edition can be done. Although these 2 platforms are very old, I'm still using them and I believe it still has a few users. .NET programming for Windows Mobile is supported in Visual Studio 2008 or below, so it shouldn't be difficult making the Windows Mobile version.
9. About multiplaying on LAN
The computer room in my school often has no Internet access (controlled by the school network center, i.e. the teachers), so we can only play games with LAN multiplaying function. Unfortunately osu! doesn't support it. Since osu! supports Internet multiplaying, I think adapting Internet multiplaying to LAN multiplaying should't be difficult.

That's all. Let me know your views about these please.

1. You can use such a search on the website, but not in-game. I'm not sure it's necessary; try using grouping modes to drill down creators instead.
2. Just use favourites?
3. '4'. Also customisable and viewable in options.
4. They are already highlighted (should turn a lighter shade of blue).
5. Please see the skins forum. A proper system may be made at some point, but this is not a high priority for me (anyone willing?)
6. F4 -> Advanced -> set a mode -> F5
7. Not changing now. Already tens of thousands of scores which cannot be adjusted easily.
8. Not intended behaviour. osu! is a game, not a movie player.
8 (#2?). I know nothing about osu!droid.
9. No plans for this.

chan wrote:

Guidelines:

1. Keep to one request per topic.

also i dunno how to even tag this one ._.
resolve,invalid and dupe?

why the hell not, let's oblige tons of requests with tons of tags \:D/

btw, reason for duplicate is...

jack980517 wrote:

9. About multiplaying on LAN
The computer room in my school often has no Internet access (controlled by the school network center, i.e. the teachers), so we can only play games with LAN multiplaying function. Unfortunately osu! doesn't support it. Since osu! supports Internet multiplaying, I think adapting Internet multiplaying to LAN multiplaying should't be difficult.

t/31320?hilit=LAN

there may be other dupe's. but thats the one that i knew of

deadbeat wrote:

chan wrote:

Guidelines:

1. Keep to one request per topic.

also i dunno how to even tag this one ._.
resolve,invalid and dupe?

I'm sorry, this is my first time posting on "Future Request" section, and I didn't read the guidelines well. I realized this when I posted it and saw the "Promote this request" button. I'll be ware of it next time. It's my fault. Do I need to write them again in 9 seperate posts?

no. it's a bit late. but next time. 1 request per topic

peppy wrote:

4. They are already highlighted (should turn a lighter shade of blue).

Lighter blue is not bright enough I think. What about orange, like the highlighted window buttons on the taskbar in Windows XP?