Such adverbs include certain adverbs of place (ones that tell where the verb's action takes place), intensifiers and moderators (ones that tell how much, such as "very"), adverbs of time (ones that tell when) and adverbs of manner (ones that describe how).
Following are some of the most common adverbs that don't end in -mente, along with their approximate meanings and sample sentences. Note that many of the words on this list are frequently used as other parts of speech, especially adjectives, so you need to rely on the context to tell you if indeed the word is being used as an adverb.
ahí — there — Duerme ahí. He is sleeping there.
ahora — now — Come ahora. He's eating now.
algo — somewhat — Está algo cansada. She is somewhat tired.
allí — over there — Duerme allí. He is sleeping over there.
aquí — here — Edison durmió aquí. Edison slept here.
ayer — yesterday — Trabajaba ayer. He was working yesterday.
bastante — rather, sufficiently — Corre bastante mal. He runs rather badly.
bien — well — Corres bien. You run well.
demasiado — too, excessively — Come demasiado rápido. He eats too fast.
despacio — slowly — Anda despacio. He walks slowly.
mal — badly, poorly — Corres mal. You run poorly.
mañana — tomorrow — Trabajaré mañana. I will work tomorrow.
no — not— No come. He isn't eating.
nunca — never— Nunca trabaja. She never works.
mucho — a lot— Habla mucho. He talks a lot.
muy — very — Estaba muy cansada. She was very tired.
poco — a little, "un-" or "in-" — Estudia poco. He studies a little. Este coche es poco económico. This car is uneconomical.
nada — not at all — Estudia nada. He doesn't study at all.
siempre — always — Estudia siempre. She is always studying.
tan — so— La vida es tan buena. Life is so good.
ya — yet, now — Viene ya. He's coming now.