There's a big group of Croatian verbs (in fact, there are thousands of them) that are quite similar in many aspects. Let's see their common features and meet the most important ones.
These verbs are mostly older and less older loans, that is, words taken from another language. For instance, old loans in English are "collect", "connect", etc. The Croatian verbs I'm talking about are most often taken from German. This is one example:
analìzīrām, analizírao "analyse"
This verb is the way to say "analyse" in Croatian — there's no other way, actually. If you have some knowledge of German, you will immediately see that it's quite alike analysieren. It even has the stress on the same syllable.
These verbs (there are thousands like them!) always have such endings (in fact, they are absolutely regular a-verbs) and accents like the verb above. Since such verbs are often used, you can immediately guess where the speaker comes from: if the present is stressed as analiziram, he or she is from the North (around Zagreb) or the West (Rijeka, Pula, some islands). Otherwise, ones who use the Standard analiziram are from elsewhere or use the Standard accent (you hear it in TV news).
Furthermore, the above verb is impf. and does not have the real perf. pair — it stands for an action that takes some time. Most of the -iram verbs have only impf. forms — they are then used in both aspects.
Many such verbs are normal Croatian verbs. But some of them are just a "scientific" or "learned" way of talking. For instance, there are two verbs meaning "correct": one is ispravljam ~ ispravim, but there's also "learned" korigiram (only impf.), obviously from German korrigieren. Such "learned" verbs are not used by common folk too often.
Croatian is unlike English — there are some people in Croatia (they include "language police", but also some others) — who are afraid of foreign verbs in Croatian. So not all words in Croatian are "acceptable" by all — this also depends whom you are talking to. About a thousand of -iram verbs are "acceptable", but there are much more. However, there are many verbs where a replacement is hard to find. Some examples are (I list here only presents since they are all a-verbs):
asfaltiram "asphalt, pave a road"
fotografiram "take photos"
miniram "mine (put explosives)"
pakiram ~ s- "pack", "wrap"
parkiram "park (a car)"
planiram ~ is- "plan"
studiram "study (on university)"
tuširam "shower (wash)",
There is no other way to say "plan" (verb) in Croatian but planiram! It's a very often used verb as well. The noun is just plan mi "plan"
Bear in mind that everything I wrote for analiziram holds for the verbs above (esp. the stress), except that a few has perf. pairs. Unfortunately, one has to memorize which ones have a perf. pair, and which do not. However, the perf. verb is always created by adding a prefix. Unfortunately, the prefix must be learned — there's no rule. So, mixed blessings.
All such verbs have either an object in acc. or no object at all (eksplodiram). Most of them that can have an object also form the mediopassive with se. They are never dative verbs or similar.
Some verbs are often used but sometimes "original" Croatian verbs are used instead:
blokiram "block" (also zaustavljam ~ zaustavim,...)
emitiram "emit, broadcast" (also odašiljem)
faširam "mince (meat)" (also meljem, mljeo,...)
garantiram "guarantee" (also jamčim)
kopiram "copy" (also preslikavam ~ preslikam)
kreiram "create, design" (also stvaram ~ stvorim, etc.)
servisiram "service, maintain" (many verbs with similar meanings exist as well...)
Sometimes there's a subtle difference in meaning. The verb kreiram involves "creativity", "imagination", while stvaram has more to do with "effort"; however, both mean basically just "create". Some are ambiguous, like servisiram: it can mean several things: "maintain", "serve", "repair", etc. It's not considered acceptable by some people, considering it "bad Croatian".
There are even some verbs that are formed with -iram but out of Croatian words, and not foreign ones: an example is lažiram "rig, manipulate". Some others that seemingly fall into this group are actually completely unrelated (e.g. biram "choose" has -iram) so most things said above don't apply to them.