The City of Chicago, as part of its Open Data portal initiative, has posted lobbyist data for 2010 and 2011 online:

Lobbyist Registry for 2010:
data.cityofchicago.org/Government/Lobbyist-Data-2010-Lobbyist-Registry/2ft4-4uik

Lobbyist Registry for 2011:
data.cityofchicago.org/Government/Lobbyist-Data-2011-Lobbyist-Registry/tpf5-fgtw

Lobbyist Compensation Report for 2010:
data.cityofchicago.org/Government/Lobbyist-Data-2010-Lobbyist-Compensation-Report/ina9-6kq2