You chat with someone and you and your chat-partner use different programms. Most of the time, if you use a smilie your partner can't see what you ment

I have often to write chemical formulas, e.g.:

NH_4 Cl + H_2 O "<->" HCl + OH^"-" + NH_4 ^"+"

this arrow ("<->") should be like in this wiki-article:
Gleichgewichtspfeil

It would be extremly useful to implement this, because rightarrow or dlrarrow are not the same

edit: I don't want to replace any arrow. I want to add this arrow - and its not the same as the arrow for resonance (I'm sorry, couldn't find it in the english wiki):
"Dies wird durch den Mesomeriepfeil (Resonanzpfeil) ↔ symbolisiert, der nicht mit dem ein chemisches Gleichgewicht symbolisierenden Doppelpfeil \;\leftrightharpoons\; verwechselt werden darf." http://de.wikipedia.org/wiki/Mesomerie

means: the arrow for resonance may not be mixed up with the arrow for chemical equilibrium

Since I code very often little PHP-Scripts which I have to print it would be nice to have a Code-Function that formats the marked area the following:

* Monospace font, e.g. Courier New
* Little, e.g. 10 pt
* Number lines - optional, you should be able to set the startnumber
* syntax highlighting like http://www.mediawiki.org/wiki/Extension:SyntaxHighlight_GeSHi/de
* you should be able to choose the language (c++, PHP, Java...)

perhaps you could use the syntax highlighting of kate or gedit

Do you know Foxmarks? Its an easy way to synchronise bookmarks and to save them. With foxmarks I don't have to worry about having saved all my bookmarks before I reinstall Ubuntu because they are not only local on my pc but also on a server.

I would like to have the same for my packages. It would be great if I could just create an account and automatically save the packet names I have installed (e.g. apache2, php5, vlc - just the names, not more). So if I would re-install ubuntu, I would just access my account and ubuntu would install the packages I had before.

This feature could also be connected with the popularity contest - so people would take an advantage of this contest and you would get better results.

##########################################
Answers to the Comments:
##########################################
Why don't make a shell-script like $ sudo apt-get install apache php vlc?
1. comfort: Especial for newbies' it's much easier if they don't have to code anything
2. no disadvantages: You should not have to use this if you have doubts where this information
goes to (just like you don't have to use the popularity contest) and I think this would not influence
the performance.
3. so why not?
##########################################
Why don't use this procedure?
On the source machine:
$ dpkg --get-selections > /some/file/called/my-packages.txt

On the fresh destination machine:
$ dpkg --set-selections > /wherever/you/put/my-packages.txt
$ apt-get dselect-upgrade


[....]