I am using openelec.tv for my raspberry pi and it runs fine, however no addons are showing up when I try download them.
I have run xbmc on my own computer and the addons appear so I am not sure what I can do to fix.
When I did a test run of this on OpenElec XBMC I noticed the same issue.
I was trying to get it to run with a WiFi USB (supported or unsupported I could not get it to work)
By default XBMC will ALWAYS USE LAN even if you set-up up WiFi. Make sure your LAN gives out DHCP and that the default gateway is set.
After I plugged in my LAN cable it took about 10~15 minutes and all the add-ons started to show up. For the first time something runs in the background each add-on one by one to make sure they are stable or if new versions are available. During the initial 10~15 minutes I got message like "plugin-b.x is no longer supported - Would you like to remove it from the plugins source" I pressed no (but in the list it marked as unsupported/broken)
After that I could download any plugin I wanted. (except iPLayer for BBC which I really really really wanted.. damn :( but most of the others are there. The GUI is slow compared to PC but it still is very impressive as it plays Xvid, DivX out of the box! about 15fps on ModelB and Full 30fps on H264! nice)
I read the is a secret console available for debugging.. try and read up about that. It might be that even you have DHPC the XBMC cannot find its way to the internet for one or another reason like DNS, GateWay, OLD IP.. etc
Choose Programs, then your OpenElec settings. Under Network, use WLAN, then wlan0 and put in your settings. Under Network 2, choose NONE for the second adapter. This will force your XBMC OpenElec build to use WiFi only.
Try using Samba if you have a Mac, or ssh. That worked for me. BTW, did you "install from the zip file" or just "install addons"? Also, you can try the Ethernet connection rather than using WiFi adapter.