Here is some essentials online tools that deserves to be known:

1 Minify your php script with minifyPHP

2 Minify your javascripts with jscssminifier

3 Un-minify your javascripts with jsbeautifier

4 Compare two files online with diffnow

5 A web interface to connect to your ftp server: net2ftp

6 Take a snapshot of a website with different browsers and screen sizes with browsershots

7 Create a favicon online from an image with this service from chami.com

8 Crack your pdf online with pdfcrack

9 Decode a barcode by uploading an image to onlinebarcodereader

10 Download every online video with keepvid

11 Create an animated GIF with GifMaker

12 Create a custom map from OSM datas with Maposmatic