I just got the Odyssey PC625 battery and I wanted to get some type of trickle charger to go with it (there are times in the year when I won't ride for awhile). I remember seeing a post from Flip about how the AGM (?) batteries don't do well with trickle chargers. The guys at the place I bought the battery from (who operate the www.odysseybatteries.com website) confirmed what Flip said and recommended a charger that works perfectly with AGM batteries.

Its a ACI Supercharger BCSC 3a ( http://www.odysseybatteries.com/accessories/aci.htm). Cost $60, has a lifetime warranty, and can both charge a dead battery and/or keep a battery completely charged up (e.g. like a trickle charger). It also comes with clamps that you can use to charge up even a car battery. They recommended this charger over Odyssey's own chargers.

On a side note, the Odyssey is a big improvement over the OEM battery. Nice to know the bike is going to start when you turn the key.