user703: I am looking for a database of chess problems in electronic format with solutions. Ideal variant will be a database with something like: 

FEN starting position *
description (Mate in 3 moves, Win material, Black to draw)
solution *
strength of the problem

Only * are really needed, other things just nice to have. It does not matter whether the resource is free or paid. Of course I can get some books and extract such positions by myself, but I hope that someone already have done something like this.

user3563: I really like ChessTempo for tactics training. Not sure if there is an option to download problems though.

user3405: If you are looking for tactical puzzles, there is always CT-Art from Convecta. You can also try Tactic Trainer for Android. It has a nifty difficulty rating system.
Also there is an online resource I forgot to add : http://www.yacpdb.org/

703: <p>I am looking for a database of <a href="https://chess.stackexchange.com/q/2145/703">chess problems</a> in electronic format with solutions. Ideal variant will be a database with something like: </p>

<ul>
<li>FEN starting position *</li>
<li>description (Mate in 3 moves, Win material, Black to draw)</li>
<li>solution *</li>
<li>strength of the problem</li>
</ul>

<p>Only * are really needed, other things just nice to have. It does not matter whether the resource is free or paid. Of course I can get some books and extract such positions by myself, but I hope that someone already have done something like this.</p>
 3563: <p>I really like <a href="http://chesstempo.com" rel="nofollow">ChessTempo</a> for tactics training. Not sure if there is an option to download problems though.</p>
 3405: <p>If you are looking for tactical puzzles, there is always CT-Art from Convecta. You can also try Tactic Trainer for Android. It has a nifty difficulty rating system.</p>

<p>Also there is an online resource I forgot to add : <a href="http://www.yacpdb.org/" rel="nofollow">http://www.yacpdb.org/</a></p>
