After nearly 3 months in Morocco, I can recommend Maroc Telecom's 3G prepaid Menara card.
€ 18,- / month for unlimited 3G access with reasonable performance and coverage. The network is a bit overbooked so it gets slow at peak hours - but overall it's price and performance is worth it.
The new INWI (former WANA) is trying to get a piece of the action also selling EVDO based USB modems. (no simcard required) A somewhat alien standard in a dominated UMTS/HSPA region since it can not be re-used in nearby Europe. For US travelers INWI might be an option - though coverage is limited to the bigger cities.
Read all about the competition of Maroc Telecom here:
3G prepaid EVDO and HSPA in Morocco
Cheers!