How far searching the web from inside email is useful is unknown but Gmail bringing you this feature.

What it makes  difference with conventional ‘search web’  option  is, you can have the search results in the same Gmail window. If you want to share the results  you can  directly paste the results into your mail compose box with single hit.

To have Search (inside) feature in Your Gmail first you have to enable (Goto Settings -> Labs ->Google search-> enable).

As shown in the picture, after enabling the feature, Google icon will present in the compose box menu.Click the icon to open the search box.

After the search results display, you have the choices to ‘ Paste result’, ‘Paste URL’ or ‘Send by email’.

>Check one more Tip : multiple inboxes