Other uses of ばかり, as found in my Canon Wordtank: 1) 出張で一週間ばかり九州に行ってたんです。"I have just been in Kyushu for *about* one week." And コップに半分ばかりの水が入れっている。"The cup is *about* half full." 2) あとは寝るばかりだ。*All that's left to do* is sleep. 3) 彼女は泣かんばかりに訴えた。She pleaded *on the verge of* tears.
There's also the present progressive form ～てばかりいる
as in: "友子は遊んでばかりいる" = Tomoko is doing nothing but playing.
and the [i]quantifier[/i] + ばかり
as in: "私は一月ばかりパリにいた" = I was in Paris for about a month.
As Adam Milazzo wrote in his website (http://www.adammil.net/japanese/esog/v49_bakari_.html)
くらい (kurai) and ほど (hodo) may also be used in this pattern, replacing ばかり. Both ほど and ばかり can also be used when referring to an exact amount (their usage makes the sentence seem a bit less direct), whereas くらい always refers to an approximate amount (and thus cannot be used with an exact amount).
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[/list]一時間ばかり勉強した。= I studied for about an hour.
In this sentence, ばかり can be replaced with either ほど or くらい, with the meaning of "about".
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[/list]そのりんごを二つばかりください。 = Please give me two of those apples.
In this sentence, ばかり can be replaced with ほど, but not with くらい, because although ばかり／ほど would seem to imply a meaning of "approximately two apples", the actual meaning is exactly two apples, because they are obviously sold in whole units. ばかり, then, serves as a softener. くらい, which always has the meaning of "approximately", cannot be used with an exact quantity. (Though perhaps you could use it if you really wanted to say "approximately two apples"?)
Strange that it isn't mentioned here, but the construction is fairly straight-forward. It directly follows a quantifier, which can either be a counter (e.g. 五分間ばかり - about 5 minutes) or an explicit number if its meaning is clear enough from context (e.g. 四十ばかり - around 40).
