Where is my Steam inventory?
Solution 1:
From either the Steam Store or the Steam interface, click the "Community" link, and you'll be taken you your "Steam feed." From here, the inventory link is on the right hand column, as shown below:
Note that you might have to change the tab, or check your Gifts in order to see everything there is to see in your inventory. The default is to display your TF2 items, whereas game gifts and so forth will show up in different parts of the interface:
Solution 2:
The easiest way to get there is in the "My Profile" menu.