Question about "-то"

I've been reading a lot of Russian lately, and I don't quite understand the function of "-то" at the end of certain words. I know that the words "когда-то" and "кто-то" mean somewhere and someone, but in the latest story I've been reading, I've come across "я-то" and "мы-то". Specifically, in these contexts:

На себя посмотри, - фыркнул Игорь. - Я-то - в отличной форме.

and

Но мы-то сейчас вес не сбрасываем, - попытался Сергей вернуть разговор в прежнее русло. - Значит, можем оттягиваться.

I don't quite understand. What is the function of -то? Also, Глупость какая-то - "какая-то" in this instance means "such stupidity", yes?

On that note, I'm also not entirely sure about либо, like "какой-либо". Could anyone please clarify?

Спасибо за ответы заранее!

1) -то added to relative/interrogative pronouns makes indefinite pronouns as like as in English adding "some...":
кто - who, кто-то somebody
где - where, где-то somewhere
почему - why, почему-то - for some reason
какая- which, какая-то - of some kind
etc.

Глупость какая-то
means "It's a stupid thing of some kind" or "It's a kind of stupid thing"

2) with other words -то has a meaning of emotional emphasis and is used in colloquial speech.

На себя посмотри, - фыркнул Игорь. - Я-то - в отличной форме.

"As for me, I am in excellent shape"

As for difference between indefinite pronouns formed with -то, -либо, - нибудь, look, for example, here:
http://masterrussian.net/f15/то-нибудь-либо-14825/

As a student of Russian, I can give you my personal observations and understanding of the differences between these words, but you should take it as that--not a perspective of a native speaker, so I may have misconstrued something along the way.

-то, -нибудь (which you didn't mention, but I'll toss it in here anyways), and -либо are all indefinite pronouns.

I'm not sure whether you know much about English grammar, but succinctly put, indefinite pronouns are just pronouns that aren't specific (definitive) about which noun they replace.

Russian has two forms of indefinite pronouns, the specific and non-specific variety. I'll also point out that while there's two types of indefinite pronouns, one of the types (the non-specific variety) has two different forms.

-то is the specific type, and нибудь and либо are of the non-specific type.

Simply enough, the specific type of indefinite pronouns refers to situations where the pronouns have a definite existence, whereas the non-specific type may or may not exist.
If you say Кто-то you're referring to a person who does exist, you just either a) don't know their name b) don't want to say their name c) don't know who they are (but know they do exist).
If you say кто-нибудь, you're referring to a (potential) person, but you're doing so without certainty as to whether they exist.

The differences I just mentioned above are the extreme differences, many times these pronouns are interchangeable. One way I can try to explain it:

If you're asking a group of kids which one of them stole a cookie from the kitchen, you can say 'Кто-то', because you know for a fact it was one of them that took it.
If you're asking a group of kids IF one of them stole a cookie from the kitchen, you can say 'Кто-нибудь', because you're not certain whether it was one of them or not.

If you say что-то, you're referring to something that is concrete, you just don't know what (or don't say what).
If you say что-нибудь, you're referring to something that potentially exists, but it is not for sure.
Что-то произошло. Something happened. (It's a fact that something of definite existence occurred, it's just not specified/known exactly what it was.)
Что-нибудь происшло? Did something happen? (Whether something has a definitive existence is not definitive.)


A good rule of thumb is if you take the 'some-' form in English and can logically add 'or other' directly after it, you should use нибудь.

Again, I'd like to re-emphasize two things:

First, I'm not saying these are definite rules, because I don't think there are any real rules that cover these pronouns. Many times they are interchangeable, and they change on a contextual basis. I just wrote the above post because it might give you somewhat of a framework to use when differentiating between these indefinite pronouns, but not a key.

Second, I'm not a long-time student of Russian, and that these are just my personal observations. It would be great if a native speaker could read over them and correct anything that I've misunderstood.

Cheers!

i think it can serve to soften statements, so they don't seem so abrupt or demanding:

В сельскую больницу Анисья приехала за тридцать вёрст.
Выехала на рассвете и в полдень остановилась у белого одноэтажного дома.
— Хирург-то принимает? — спросила она мужика, сидевшего на крыльце.
— Хирург-то? — с интересом спросил мужик.— А ты не больна ли будешь?

Anisia traveled thirty versts to get to the country hospital.
She set out at dawn and at noon she paused before the white
single-storied house.
"Is the surgeon receiving?" she asked a peasant sitting on the
porch.
"The surgeon?" the peasant asked with interest. "What, you
sick?"