The Thai word for blog is บล็อก. I have no clue what the อ็ is doing here. I only know of two uses for this mark: replacing the อะ in เอะ (and แอะ, mostly in loanwords) if it's followed by a consonant (เกะ but เก็บ) and in the linking particle ก็, which is pronounced like เก้าะ or ก้อ.
Okay so what is that thing called anyway...
It's called ไม้ไต่คู้.
The wiki entry only lays out the two uses I already mentioned. Interesting it gives น็อก as an example of the อะ replacement rule. This confuses me. น็อก is pronounced with a high tone, where นอก would be falling. อ็ must indicate a shortened vowel (which would raise the tone).
Since it only seems to occur before the vowel ออ, I'm going to assume that อ็ is specially used to shorten this vowel only. A short ออ is normally written as เอาะ, which is a strange mess of characters. If you wrote น็อก using this form, it would be เน็าก, which is very confusing.
My hypothesis is that อ็ is used to shorten the vowel อ in loanwords, simply to avoid confusion. The pronunciation of บล็อก is /bàlɔk/, the 2nd syllable being high, which is consistant with this.
Of course, now I notice that เอาะ is listed in the wikipedia entry as a vowel that อ็ acted upon, and the matching example is น็อก. I'm also noticing that the pronunciation of ก็ I gave was a pretty huge hint as well. Oh well, it's fun to work these things out on my own.
น็อก, by the way, is a borrowing of the English word "nock". While looking all this crap up, I stumbled upon the Thai word for crash-helmet:หมวกกันน็อก. Literally, "knock" hat.