  We present a multiwavelength study of the unidentified Fermi gamma-ray source
0FGL J1830.3+0617, which exhibits variability above 200 MeV on timescales of
days to weeks. Within the Fermi 95% confidence error contour lies B1827+0617, a
radio source with spectral index alpha = 0.09 between 1.4 and 4.85 GHz. The
flat spectral index and flux density of 443 mJy at 4.85 GHz are consistent with
the bulk of Fermi sources associated with blazars. It is also detected in the
0.3-10 keV band by Swift. Optical imaging in 2009 May identifies B1827+0617 at
R ~ 16.9, and shows that it is at least 2 magnitudes brighter than on the
Palomar Sky Survey plates. Contemporaneous optical spectroscopy acquired during
this high state finds a weak emission line that we attribute to Mg II at
redshift z = 0.75, supporting a flat spectrum radio quasar (FSRQ)
classification. The variability characteristics and radio properties together
indicate that 0FGL J1830.3+0617 at Galactic latitude b = 7.5 degrees is a
blazar. Blazar identifications of three additional low-latitude Fermi sources,
0FGL J0643.2+0858, 0FGL J1326.6-5302, and 0FGL J1328.8-5604, are also
suggested.
