I am driving a Tacoma extended cab with a Clarion HU and 5 1/4" Clarion
component speakers up front running off deck power only. I also have a MTX
monoblock amp and JL 10" sub that easily overpowers the components
(obviously).

I want a 2 channel amp to power the front speakers. I realize that the HU
and speakers are not super high quality so I don't need an amp that is too
powerful. I might upgrade the front speakers in the near future to a set
of Focals. I have no intention of using much of the rear speakers but I
might one day replace the stock rear speakers with my current Clarion
components and plan to run them off deck power only.

Any suggestions on an amp that would fit well with my current stuff?

BTW, has anyone any experience fitting 6 1/2" component speakers into the
front doors of a 2003 Tacoma? I once tried to fit some Rockford Fosgates
there but the magnet was so big that it would not fit past the metal
bracing of the window sliders and it was so deep that even if it did fit, I
would need to carve up the door trim. I have seen other good quality
speakers with much smaller magnets, and I have been told that size doesn't
matter (my wife says so anyway, God love her), but if you could recommend
specific speakers that are sure to fit, I would appreciate it.

Thanks in advance.

You can Google up the many long threads dedicated to this subject. The plain
and simple truth - despite what many "enthusiasts" may tell you - is that there
is no "best" amp. Most of today's quality amps perform so well that the human
ear cannot detect any important differences between them under properly
conducted blind-testing. Look for something slightly more powerful than the RMS
rating on the speakers and there's little chance of you ending up unhappy.
Alpine, Pioneer, Blaupunkt, Eclipse, Jl Audio and Phoenix Gold all make fairly
inexpensive amps that'll get the job done right and with quality. Zapco's new
iForce line is worth a look too, as are the A/D/S products.