  During the first two years of observation, AGILE detected several blazars at
high significance: 3C 279, 3C 454.3, PKS 1510-089, S5 0716+714, 3C 273, W
Comae, Mrk 421 and PKS 0537-441. We obtained long-term coverage of 3C 454.3,
for a total of more than three months at energies above 100 MeV. 3C 273 was the
first blazar detected simultaneously by the AGILE gamma-ray detector and by its
hard X-ray monitor. S5 0716+714, an intermediate BL Lac object, exhibited a
very fast and intense gamma-ray transient during an optical high-state phase,
challenging the current theoretical models for energy extraction from a
rotating black hole, while W Comae and Mkn 421 were detected during an AGILE
Target of Opportunity (ToO) repointing, and were simultaneously detected by
Cherenkov telescopes. Thanks to the rapid dissemination of our alerts, we were
able to obtain multi-wavelength ToO data from other observatories such as
Spitzer, Swift, RXTE, Suzaku, INTEGRAL, MAGIC, VERITAS, as well as
radio-to-optical coverage by means of the WEBT Consortium and REM, allowing us
to study truly simultaneous spectral energy distributions from the radio to the
TeV energy band.
