There are a huge amount of users who use Google Reader to manage their RSS subscriptions. These shortcut keys for Google Reader will help you boost your productivity and save some time while reading your sucbcriptions.

Column 1 Column 2
J Selects Next Item in list
K Selects Previous Item in list
Space Page Up
Shift + Space Page Down
N Next Item in list view
P Previous Item in list view
O Expand / Collapses any selected item
Enter Expand / Collapses any selected item
S Star an item
Shift + S Share an item
M Mark item as Read / Unread
T Tag an item
V Open article source code in new window
Shift + A Mark all as read
1 Expand all subscriptions
2 Headline views all subscriptions
R Refresh feeds
Shift + N Next in subscriptions
Shift + P Previous in subscriptions
Shift + X Expand / Collaps folders of subscriptions
Shift + O Open selected subscriptions
G H Go back to Home
G S Go to Starred items
G T Launch Tag and browse by Tag
G U Launch Subscription and browse Subscriptions
U Hide / Show Subscription Panel
Shift + ? Where I got this list from. Reader shortcuts in Popup :-)
Alt + F4 Time to get back to work