I have A Guide To The Birds Of Mexico And Northern Central America, by Howell and Webb. Hard to tell from your photos, but based upon the two white lines on the throat bordering a black streak, the white patch on the lower back, and the white ring on the edge of the tail, my guess is a female Plain-capped Starthroat or Long-billed Starthroat. Males have a small spot of red covering the lower-half of the throat. Both species show ranges through your area.

Bruce C.

I checked and both of these are also in my book...but they don't look anything like mine, in 'real life'!
It does make sense though, as it does say, the plain-capped are in my area.
The 'streaks by the eyes seem much wider and more visible
. I have added a cropped photo that might make it easier...which I should have done in the first place.
http://i4.photobucket.com/albums/y136/costaricafinca/Unknown%20Hummingbird/crop5.jpg
http://i4.photobucket.com/albums/y136/costaricafinca/Unknown%20Hummingbird/crop3.jpg
http://i4.photobucket.com/albums/y136/costaricafinca/Unknown%20Hummingbird/crop2.jpg
http://i4.photobucket.com/albums/y136/costaricafinca/Unknown%20Hummingbird/crop6.jpg
http://i4.photobucket.com/albums/y136/costaricafinca/Unknown%20Hummingbird/crop7.jpg

Here is a link that might be useful: {{gwi:989056}}

Don't have time right now to scan the drawing from my book, but it really looks like a dead-ringer for your bird. Sorry I can't offer any alternate possibilities. Unfortunately, Googling for tropical hummer photos doesn't come up with many decent pics. Keep in mind that hermits have curved bills, which yours does not. Also, local populations of birds can have subtle variations in coloration.

Bruce C.